This will show you how to remove the outer case so you can make replacements within the device.
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.
After removing the back pad, unscrew the five 5 mm Phillips #00 screws in the large, deep holes in the plastic casing. The plastic casing should come off easily after removing all the screws.
Insert a narrow plastic opening tool into one of the notches. Apply moderate force to pull the metal casing from the plastic outer casing. You can use the rim of the outer case as leverage. You should hear a click when the metal casing detaches.
After you hear the click, remove the inner metal case from the outer case using your hands. It should not take very much force.