CAUTION: The heat gun and hair dryer can get very hot. Do not put your hands or any other body part too close to either device. Also, do not touch the back pad right after heating it.
Use a blow dryer or heat gun on a medium to high heat setting on the back pad to loosen the glue that attaches it to the device.
To avoid ripping the back pad, gently peel it back from one corner until the pad is completely off.
Use heat in areas where the glue is not loose enough.
You may need to reattach the back pad with double-sided tape if the glue is not tacky enough to stick the pad back on.