Heat with Soldering Iron and pry up the cathode of the battery. Please do not touch the aluminum foil while applying heat to avoid damaging the plastic case. Since the anode of the battery is on the other side of the cathode of the flex cable, we need to pry up the flex cable.

Keep applying a small amount of Paste Flux. Heat with Soldering Iron to separate the anode of the battery from the flex cable.

Remove the anode iron plate of the battery with a Cutting Nipper.