The battery should be located in the upper handle of the Pipet Aid. Unplug the connector from the board of the controller by pulling on the white clip containing the black and red wires.

Once unclipped, the battery might be held down by adhesive. This can be removed with some isopropyl alcohol and some pulling force.

Replace the battery by plugging into the board or connector (this depends on your model) and tucking the wires next to the battery.