He put gum on the damaged screw. This brilliant trick is useful to everyone!

Anyone who has made repairs in the apartment, faced with this problem: the screw closely drawn to the surface, and the slot (slot on the head of the fastener, which is inserted into the end of a screwdriver) derailed tightly. Accordingly, to unscrew a screw problematic. This occurs most often with faces under the Phillips screwdriver
You can try to unscrew the screw with pliers, but it does not always help. If drilled cap, the screw may remain permanently in the material body.

But do not despair, unscrew the screw with torn edges
How to unscrew the screw

Pick rubber gasket