At present, the general household smart locks have four methods of fingerprint, IC card, mechanical key, and password unlocking. Some people are very curious. Why does the smart lock still have the mechanical key unlocking method? This is mainly because the manufacturer follows the traditional door lock to unlock. The way to keep the mechanical key is to give the person who used the key a sense of security. The smart lock usually prompts the user to change the battery quickly by voice prompt or bright light when there is no power. Once the power is cut off, it can only be outside the door. Temporarily power the smart lock to open the door by using mobile power.