The next steps detail how to install a new battery. Never reinstall a used battery.

Thoroughly clean the back case of all adhesive residue.

Apply adhesive remover or high concentration (over 90%) isopropyl alcohol to the residue.

Use an opening tool to scrape and loosen the residue.

Be sure to wipe the residue away in one direction to prevent smearing.

It is easier to wipe off the residue when it is sufficiently soaked. Once it starts drying up, the residue becomes incredibly tacky.

If you used adhesive remover, be sure to wipe the surface down with isopropyl alcohol to remove any adhesive remover residue.

You can remove the masking tape as well as any protective gear once you are done cleaning.