1. Entering the locked state: Press the "Lock (F2)" key directly on the POS front-end interface, and the system will immediately enter the locked state. The screen will turn black and all sales functions will be temporarily locked to prevent others from operating.

2. Unlock interface: Press the "Lock (F2)" key in a black screen state, and the system will pop up a password input window. The operator must enter the correct password to restore the normal working interface.