Remove the back of the tablet by heating the back with the heat gun. Careful not to damage the plastic.

Push a sharp blade 2-3 mm in between the metal edge and plastic back.

Pull the plastic back away from the metal shield underneath. The adhesive bonds is much stronger to the metal than the plastic, so try to leave the adhesive on the metal.

If the adhesive folds over onto itself use the sharp knife to cut it off and remove it from the metal.