Unscrew the circular cover located in the lower part of the brush. She rolled out of battery. After three months of use, it will, of course, almost empty, but her charge is enough for work during a period of low power load. Try to connect it the right polarity, for example, an electronic clock with LCD indicator, or a homemade led flashlight with a Converter of the type Joule Thief. In any case, place the battery inside does not load, and the outside: despite the fact that the brush is sealed from the inside, to the end of the useful life the seal is broken and the battery is showing the first signs of corrosion.
Then pull the plastic frame with the engine. For this you will need miniature pliers. Pliers will not fit. Will recepite two latches, which frame is attached to the brush body, and then pull it on themselves.
On the frame you will find a simple toggle switch and the engine. Separate them from each other. If they are wet, wipe them dry, then dry.
If you decide to give your child homemade electroconstruction, the switch and the engine will be very handy. Provide first dielectric pushers of any design. Then install these parts on the stand, they are the same place and clamps for connection to other circuits. It remains to connect in parallel with the engine Dohnanyi Zener diode 10 volt (or its equivalent of two Zener diodes connected in series cathode to cathode). This is necessary to protect children's fingers from bursts of self-inductance. Remember that this engine is designed for a voltage of 1.5 V.
It remains to find a use for the brush. Remember how often the house master have to wash plastics. Toothbrush, more unusable for its intended purpose, to clean plastic fit could not be better. Together with her use any means to wash dishes but in very small quantity. Of course, the housing of the electronic equipment so can only be cleaned separately from the content, and before the Assembly should be thoroughly dried.