Can't you unlock the lock with a new key?

First, open the door and try a new key. Being able to turn is not the key issue. If you can't turn the door when you open it, it's a key problem. If you can't turn the door after locking it, it's the door frame. You should clean up the particles at the handover position of the lock core of the security door on the door frame!

Related instructions

It should be noted that some key blanks are made of metal, but they are really inferior. Before long, the teeth will be worn out. These key blanks are invisible to the naked eye and can be distinguished by throwing them on hard tables such as cement floor or glass desktop. A good metal blank gives off a crisp metal sound, while a poor metal blank gives off a dull sound similar to the collision between plastic and hard desktop.

It often happens that inferior keys are broken in two, and the first part of the head is broken in the keyhole. In order to take out this half, it took a lot of effort to remove the lock, but it actually took a clever effort to solve it. Use a wooden screw (perhaps fast wire is better), carefully insert the tip of the screw into the gap between the key head and the hole, and it didn't take long to pick it out.