Hello, your not the first and definitely wont be the last screw, screw up. : ) I would first try tapping very gently a straight bladed screw driver into the old hex hole , with a thin blade just a bit wider than your stripped hex. Until you get a good bite to start removing the screw. You will have more torque force with a straight blade then with the hex and may also loosen the screw by the tapping action. By chance that doesn't work for you , you can try to get a bite of the outside screw head with a pair of small duck bill or flat nose mini pliers with teeth. Or a pair of the ifixit screw extracting pliers.Screw Extracting Pliers I would go nose down onto board(its only contact with a ground plain) squeeze screw head and turn. Only if all else fails would i think of drilling or cutting out. Hope this helps and good luck. Clyde

Have you tried reseating the battery and then plugging in a.c. power supply before trying to power on?

I followed your product link. Your probkem is listed under there second page of features. "Support android phone has OTG and UVC function after install." ( This is why phone worked. ) ("CameraFi" app )from google store,,such as Samsung Galaxy S4 S5 S6, Note 2, Note 3, Note 4, Note 5 ,HTC M9 ,M9+,M8,LG G4 etc" (So install CameraFi and you should be good to go.) Hope this helped. This is my first day on ifixit and first attempted answer..