The Oral B Sonic Complete Toothbrush is more cost efficient than some electric brushes, and offers the same "sonic" technology with thousands of vibrations per minute to aid in the cleaning of your mouth. Although built to last a few years of regular use, sometimes bad things happen to good brushes. If your brush won't turn on, try a few tricks to extend its life.
Fully charge your brush, which takes about 16 hours. If this produces no effect, move on to the next step. If it takes a small charge, then it is likely an issue with the battery not taking the charge.
Test the voltage of the charger base. This is a simple method to see if your brush is getting power from the base. Touch the metal connectors with the voltage tester. This should light up the tester. If not, it is losing electricity somewhere within the base.
See if the charging light is illuminated while the brush is on the charging base. If it is illuminated but still does not power on, it could be an issue with the power switch.
Purchase two GP100AFH NiMH rechargeable batteries.
Attach the negative end of one battery to the positive of the other using the soldering pencil. Take care not to apply too much heat to the batteries. Wrap the batteries together with insulating tape, creating one long battery.
Remove the battery/circuit board. On the back side of the charger base, there is a protrusion that can be used to unscrew the bottom of the brush. Do this, and carefully remove the circuit board, which is attached to the battery.
Carefully cut the solder that connects the battery to the circuit board. Make the cut as close to the battery as possible, leaving as much of the solder attached to the board as you can.
Replace the battery. Take out the old, and put in your newly constructed replacement. Bend the existing solder attachments on the board to make contact with the battery. Put everything back together and charge the brush. If it was indeed a battery issue and everything was done correctly, then you should have a fully operational brush once more.
Remove the circuit board. Using the same method listed above, slide out the circuit board. You'll notice that the exterior power button contacts a microswitch attached to the board.
Solder the microswitch to the board. The microswitch is connected by four small solder joints, and if any of these have been compromised, it could result in faulty operations. Use the solder pencil to attach these joints.
Re-assemble your brush and see if this did the trick. If your brush is still not working, it might be something more serious involving the circuitry.