Using a Phillips-Head #1 screwdriver, unscrew the four outer 1.0 mm screws and remove with tweezers.

Unscrew the 0.6 mm screw located in the center of the battery case.

Remove the back cover carefully; there are many wires that connect it to the device.

Keep the 1.0 mm and 0.6 mm screws separate from each other for reassembly.