Avoid using a heat gun for this step as overheating the battery can cause permanent damage.

You may use an iOpener on the front side of the phone to safely heat and loosen the adhesive under the battery.

Insert the plastic spudger into the gap between the frame and the battery.

Move the spudger around the outside edge of the battery to remove the adhesive.

Do not bend or puncture the battery. There is a lot of adhesive holding the battery in place, moving the spudger may require some effort. Use the plastic opening tools to help pry each side open.