Unscrew the battery locking screws with a small Phillips head driver and save the screws (x4).

Unclip the thin white speaker cable that runs down the bottom edge of the battery cell.

Gently pry underneath the battery with plastic spudgers to lift the battery out of it's housing, which will also disconnect the battery from the system.

NOTE: There may still be charge left in the capacitors so wait a few minutes if you plan to tear down the device any further. Also, do not bend the battery at all, otherwise you will compromise it's integrity and could damage/brick your battery and/or device.