Why can't the card made by the hotel's card lock system be opened in a few days?

Hotel key cards are time-limited, generally set according to the check-in time. If they exceed the check-in date and time, they will naturally become invalid.

In addition, the hotel needs to pay the room deposit in advance. If the room deposit is insufficient (signing the room bill, the rent is insufficient), the hotel will temporarily cancel the room card. You need to pay the deposit at the front desk and refresh your room card before you can use it.

Another possibility is that if the room card is put together with magnetic and radioactive items (such as mobile phones), it will also lead to the failure of the room card.