First, remove the black plastic cover from the back of the hair clipper, which is connected by a plastic clip without screws, just like removing a remote control. Then you can see 3 self-tapping screws and remove them with a Phillips screwdriver. Take off the end, you can see 2 phillips screws, which are fixed shell and motor, remove. Finally, separate the two parts of the white plastic housing, and you can see the circuit board, the motor and the charging socket. Generally, it is the battery aging problem, and it can be replaced by two nickel-cadmium batteries.