1. First of all, if the smiling shark flashlight can't be charged, you can disconnect the circuit and internal wiring, so as to deform the brass tube conductive sheet inside the plug, thus connecting the disconnected part or deforming the spring sheet.

2. Secondly, check the step-down capacitor and rectifier diode and replace the damaged components.

3. Finally, clean the electrode plate of the smiling shark flashlight and replace it with distilled water.