I found two good methods over the years. Automatic center punch will usually jar the screw loose enough for getting anything that fits into the screw hole and back it on out.
Should that fail, a dremel cut off tool can slot the head in seconds for a standard screw driver to back out, if your fear the tool jumping to the case, you can hold or superglue a washer over the trox screw for protection and cut into the washers open hole. These two methods have never failed me.
