Apply a suction handle to the center of the battery.

Brace the top and bottom of the device against your work surface with one hand and firmly pull up on the suction handle with the other.

The adhesive takes time and repeated pulls rather than strong force to loosen. Pull on the suction cup with steady force for 15 seconds at a time.

If the battery doesn't loosen after multiple attempts, apply 1-2 drops of isopropyl alcohol along the top, left, and right edges, wait a minute, and pull again.

Continue lifting until the battery separates from the phone.