The battery is stored in the quip's handle beneath the motor and is accessible by removing the brush head and motor. To watch a video demonstration of the battery being changed, click here!
You can remove your brush head to change out your battery by lightly gripping the handle in one hand, head in the other with the bristles pointing away from you. Gently pull the head off the handle in a slight arc motion as shown in the video below. Do not snap the head directly backwards.
Lightly wet bristles of old brush head (if you have it) and use to gently remove all dried toothpaste residue from handle. If you don't have an old brush head, a damp paper towel can be used. You can then pull the motor out using the "ears" and tip the handle and tap the the battery out.
Drop the fresh or charged AAA battery, negative end first, and slide the motor back in (it will spring up slightly!). Push the new head on until flush with the handle or you hear a dull click.