You can try this but i must warn you to be VERY CAUTIOUS in what you are doing. I used this method and it was successful for me, but then again, it was a small screw. *I am not responsible for any damage done to your phone* :)
Ok, so i took a power drill and used it on the top screw of the EMF protection shield. The screw was stripped so I took the smallest drill bit i could find that would just fit the circumference of the screw. Then, very carefully screw into it, completely making the screw into a bowl. Next, switched directions of the drill, used a little force and went slow....next thing i know the screw is out. You can try this but just be careful and don't break anything. GOOD LUCK! Let me Know if you need anything else.;