What if the smartphone doesn't turn on? 20 points

What if the smartphone doesn't turn on? 20 points

Hello, do you think the screen is on or off? It should be black all the time and there is no response. Here are some ways to tell you ... 1- If your mobile phone has a non-removable battery, please press and hold the phone room button, volume up button and power on button for five seconds, not yet, after sale! 2- Take out the battery, connect the charger and check the charger indicator. But now the chargers of smart phones generally have no indicator lights. Charge it with the charger for five or six minutes before turning it on. If it doesn't work, disconnect the battery, connect the phone and charger directly, and come back, not yet ... after sale! 3- If you have swiped the computer before, put the new swiping package into the memory card, and then get root permission again. Otherwise, something similar to the program should appear on the screen ... If not, after sale! 4- There's really nothing we can do. You can fall a few times, pat, blow, knock or something, and maybe it will be fine! I hope this is useful to you. Thank you.

What is the reason why the mobile phone suddenly doesn't work? What should we do?

There are many reasons why the mobile phone doesn't turn on: First, it doesn't turn on because the power cord is abnormal.

Under normal circumstances, when the power key is pressed, the trigger terminal voltage of the power key should change obviously. If there is no change, it is generally due to poor contact of the power key or disconnection of the power cord, virtual welding or damage of components. During maintenance, use external power supply to supply power, and observe the change of ammeter. If the ammeter doesn't respond, it's usually that the starting wire is broken or the starting key is broken.

Second, the battery power supply circuit is not turned on.

For most mobile phones, after adding a battery or an external power supply to the mobile phone, the power supply voltage is directly applied to the power supply C. If the power supply voltage is not applied to the power supply IC, the mobile phone cannot be turned on.

For Motorola series mobile phones (except Motorola T2688), the power supply is different. The battery power supply and external power supply should be converted by electronic switch before being added to the power supply ic. In other words, there are two paths for mobile phone power supply, one is battery power supply; Another way is external interface power supply (when the charger is powered on). When two power supplies supply power at the same time, the external interface supplies power first. The switches of these two power supplies are controlled by electronic switch tubes, which mainly protect the current of the whole machine and prevent the internal integrated circuit of the mobile phone from being damaged due to short circuit or leakage. However, if the electronic switch is damaged, the Zhongyuan module may not get the power supply voltage of the battery and the mobile phone cannot be turned on. For this kind of mobile phone powered by electronic switch, it can be powered by external power interface or external power supply through battery contact. During maintenance, different power supply methods can be used to distinguish the fault range and determine whether the electronic switch is normal.

Generally speaking, if the power supply line is broken, the ammeter will not respond if you press the power-on key, which is very similar to the broken power supply line.

Third, the power IC is not turned on due to abnormality.

For the mobile phone to work normally, the power supply circuit should output normal voltage to the load circuit. In the power supply circuit, the power supply IC is its core circuit. Different varieties and models of mobile phones have different power supply methods. Some power supply circuits are powered by several voltage stabilizing tubes, such as Ericsson's early series of mobile phones (before T 18) and some Samsung series of mobile phones. Some have power modules directly, such as Motorola series phones and Nokia series phones. But in any case, if the power IC can't work normally, it may lead to the phone not being turned on.

For the power IC, the key point is to check the output logic power supply voltage and the 13MHz clock power supply voltage, which should be detected (not necessarily kept) during the process of pressing the power key. If it is not detected, the power IC is damaged by welding under the condition that the power key and battery power supply are normal. At present, more and more power integrated circuits are packaged by BGA, which brings great burden to measurement and maintenance. When measuring, the test can be carried out at the test point of the peripheral circuit of the power IC according to the circuit schematic diagram. If it is judged that the power IC is soldered or damaged, it needs to be transplanted and replaced again, which requires high operating skills and needs to be honed in practice.

Fourth, the system is not turned on and reset due to abnormal clock.

System clock is one of the conditions for CPU to work normally. The clock of mobile phone system generally adopts 13MHz, and the clock of 13MHz is abnormal, so the logic circuit doesn't work and the mobile phone can't be turned on.

The clock signal of 13MHz should reach a certain amplitude and be stable. Measure the waveform of 13MHz clock output with oscilloscope. If there is no waveform, detect the power supply voltage of 13MHz clock oscillation circuit (for 13MHzVCO, the power supply voltage is added to one pin of 13MHzVCO, and for the oscillation circuit composed of 13MHz crystal oscillator, this power supply voltage is generally provided to IF IC). If the voltage is normal, then,

Note that some oscilloscopes may stop the crystal from vibrating when measuring on the crystal. At this time, a capacitor below several tens of picofarads can be connected in series with the probe. If possible, it's best to adopt alternative maintenance method to save time and improve efficiency.

After the 13MHz clock circuit starts to oscillate, ensure that the 13MHz clock signal can be input to the CPU pin through the resistor, capacitor and amplifier circuit, and test the CPU clock input pin. If not, check whether the resistors, capacitors and amplifier circuits in the circuit are welded or damaged.

In addition, the clock crystal oscillator or clock VCO of some mobile phones is 26MHz (such as Motorola V998, Nokia 33 10 mobile phone) or 19.5MHz (such as Samsung A 188 mobile phone), and the generated oscillation frequency is divided into 13MHz by IF IC before being provided to CPU.

The reset signal is also one of the working states of CPU, and the symbol is R. ......

Why can't 360 mobile phone be opened?

Hello, theme,

360 can't turn on the machine

Is it wrong to suggest changing the charger to charge the experiment first?

Check whether there is any problem with the u *** interface and charger.

If there is any problem, replace it in time.

Secondly, check whether the battery is worn.

It is recommended to go to the local maintenance point to find a professional to check.

Finally, check whether there is a problem with the system.

If it's a system problem

This happens because of your improper operation.

Commonly known as "bricks"

solution

Download the official Ruu, which is the original system Rom. Generally, Baidu can search by adding its own model.

Then press the volume button and the power off button at the same time to enter the recovery mode to brush the machine.

The first thing we need to do is the double clearing operation.

Use the volume keys to move to the two options of "Erase Date/Factory Reset" and "wipecache Partition".

Click the power button to confirm.

Then select "install zipfrom sdcard" (install zip upgrade package from SD card, that is, rom package stored in the card before).

If the fault still exists, continue to do this once and try another Rom package.

I wish the subject a smooth solution to the problem

What should I do if the 4G mobile phone can't be opened?

Possible reasons and solutions for not turning on the computer;

1. battery reason. Check whether the power is sufficient, whether the battery is deformed or loose, try again after charging for more than half an hour (suitable for mobile phones that have not been used for a while), and replace the battery.

2. Check whether the key is out of order.

3. Software reasons. For example, if you have brushed an unofficial system or ROOT, you can try the official ROM.

4. Hardware reasons. For example, the water gets wet, falls, bumps and so on. Send it for repair

5. All-in-one machine, press and hold the power button 15 seconds. If it can't be turned on, charge for half an hour and try again.

Above, for reference.

The mobile phone is always on, but it doesn't turn on. What should I do?

The reason and solution of mobile phone with power but unable to start;

1, the boot line is not normal. Look: use an external power supply to power the mobile phone, and use an electric meter to check whether the indicator light has changed. If there is no change, it is likely that the boot cable is broken or the boot key is in poor contact.

2. The battery power supply circuit is abnormal: use the external interface to supply power to the mobile phone, and turn it on to see if it returns to normal. If it is normal, it is determined that the mobile phone power supply circuit is abnormal.

3. Abnormal mobile phone power IC: Test the peripheral circuit of the power IC against the circuit schematic diagram to see if the test value is normal.

4. The system clock and reset of the mobile phone are abnormal: you can use the dual-purpose oscilloscope to detect the CPU power supply of the mobile phone and check whether the waveform in the reset is correct.

5. There is something wrong with the logic circuit: the circuit board of the mobile phone is faulty. Generally, this problem can be solved by repair welding.

6. Software conflict: The installed software does not match the system of the mobile phone, which may also cause the mobile phone to fail to boot. You can connect your mobile phone to the computer to delete the program.

Causes and solutions of failure of mobile phone charging and starting;

1. For non-original chargers, it is easy to fail charging. If the charger specification is not up to standard, replace it with a qualified charger.

2. Please check whether the data cable is normal. The data cable looks normal outside, but it may be broken inside. The inspection method is to borrow someone else's data line to see if it can be recharged.

3. The plug symbol is usually displayed when it is full. Now it's full or low, but it can show that there is no problem with the tail plug of the mobile phone. You should try the charger first. If it still doesn't work, the battery is broken.

4. Again, check whether the original charger can work normally. You can connect the charger to another mobile phone with USB port to see if it works properly.

5. If the above two devices still can't be charged after inspection, please try to plug them into the USB port of the computer to see if the computer can recognize the mobile phone. If you can, see if it is charging. If it is recognized, it is estimated that it needs maintenance. If it cannot be identified and recharged, it must be repaired. If it can be identified and charged, please replace the data cable and charger with better quality.

6. See if the voltage is too low, or go directly to the maintenance station.

What is the reason why the mobile phone suddenly can't open the opportunity?

It may be that the battery is dead, or the battery is in poor contact, or the button on the phone is broken. The most serious thing is that there is something wrong with a component inside the phone.

What if the vivo phone can't be opened?

Hello!

I suggest you try the following methods to boot: 1. Press and hold the power button 10 second to force the phone to restart. 2. Try charging for 20 minutes and then press the power button 10 second to see if it can be turned on (the phone is completely dead without prompting). 3. Press and hold the volume up button and the power button for 3 to 4 seconds at the same time when the mobile phone displays the vivo mobile phone logo, and then release the button to enter the recovery mode. First, select Erase Data/Restore Factory Settings. After waiting for the interface to jump, select Erase Cache Partition. Then, select Restart the system immediately, and restart the phone immediately after completion. (Doing so will lose all data on the mobile phone (except the data on the TF card), including installed applications, phone books, short messages, etc. Use this item only if there is a serious abnormality in the mobile phone and there is no other way to solve it. Use with caution. If the above methods still can't be turned on, it is recommended that you take your mobile phone to the local after-sales inspection and processing, and the after-sales technicians will handle it for you. You can go to vivo official website to inquire about the address of the after-sales service center: vivo/ click on the website, then click on the service, and then click on the outlet to inquire. According to the prompts, you can inquire about the after-sales address of your province and city.

If you have any questions, please feel free to consult us. Thank you very much for your support of our vivo. I wish you a happy life!

Why can't the phone be turned on when it's smashed?

Hello!

According to your description,

The problem that the mobile phone can't be turned on after being smashed,

It is recommended to try the operation according to the following steps:

The machine is fully charged, and after data backup, in the shutdown state,

Press and hold the [Power] and [Volume+] keys 10 second.

After entering the recovery mode, use [Volume+] and [Volume-] to move the cursor (see the figure below).

Wipe again for 2 times.

Select erase data/restore factory settings > yes, [home] to confirm.

Select erase cache partition > yes, and [home] to confirm.

Select restart system now > Yes, and [Home] to confirm.

Restart after this operation is completed, that is, complete.

If the problem is still not solved after 2 wipes, or it cannot be recovered at all.

It is probably a hardware problem, so it is recommended to return to after-sales maintenance as soon as possible.

I hope this can help you! !

What if Apple's mobile phone can't be opened and iphone can't be opened?

Stop 1 Mobile phones can't be turned on. There are many kinds. If there is a shutdown fault. Then we don't have to make a fuss, just press and hold the "power button" and "home button" on the top of the phone at the same time. If you hold it down and turn it on at the same time, please remember not to let go. Press and hold for about 10 second, and it will turn on normally. Jailbreak failure 1 Many users reported that after jailbreaking, the mobile phone could not be turned on at first. 2 If we find that the phone can't start after jailbreaking or upgrading the system, then we just need to connect itunes and repair it. 3 or use other mobile assistant software can also be repaired. Hardware failure 1, such as the switch button of our mobile phone or the hardware of the mobile phone. If you have experience in hardware maintenance, you can disassemble the machine for inspection. I don't advocate this practice here. I suggest sending it for warranty.

What if the phone can't get through?

Clear the information, reselect the ZIP package and refresh the machine.

Brush step

1. Download the brush package you want to brush to your SD card. The suffix is ZIP, and the name cannot be Chinese.

2. The phone is off.

3. Press the Volume Down key +Home key, and then press the Start key to enter the recovery mode.

4. Use the volume button to select clear data/restore factory settings, and clear the cache partition slot, which is also known as double erasure. After that, everything installed and stored in your mobile phone is gone. Please pay attention to backup.

5. Use the volume button to select Update and Install zip package to find your brush package from SD card.

6. Use the power button to confirm the package you selected, confirm it again, and then start to brush the machine.

7. After successful brushing, return to the superior menu. Restart the system, and then turn it on.