Remove the back of the tablet by heating the back with the heat gun or an hairdryer. Careful not to damage the plastic: try to diffuse heat and not concentrate it too much.

Push a sharp blade 2-3 mm or a plastic pick in between the metal edge and plastic back. You can help yourself with a suction cup, in order to lift the edges more easily.

Careful not to damage exposed ribon ports/cables. Check diagram in step 4 for their location.

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 needed, try to use small quantities of isopropyl alcohol to loosen the adehesive.

Using isopropyl alcohol might help you reduce damage on back cover

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

Proceed carefully and don't get upset: it can be a time consuming process. If you try to proceed too fast you could damage back cover or internals.