Apply a heated iOpener to the lower glass panel on the back of the phone for five minutes.

The panel is extremely stubborn, and you may need to reheat and reapply the iOpener several times to get the panel warm enough. Follow the iOpener instructions to avoid overheating.

A hair dryer, heat gun, or hot plate may also be used, but be careful not to overheat the phone—the display and internal battery are both susceptible to heat damage.