First, turn off the laptop and make sure it is unplugged from power to avoid injury.

Unscrew the 15 screws on the bottom panel of the computer using a Phillips #00 screwdriver. One screw will be hidden under a warranty sticker

Gently pry around the back cover off the with a plastic spudger

Unplug the battery cable from the motherboard.

Too much pressure from the spudger can break the clips that secure the back panel, but some flex is not dangerous.