You will need a drill bit about 1/2 the diameter of the head and a magnet. Taking it real slow drill through the head of the screw with the magnet very close to the head catching the chips when you get through the head it will be detached when you remove the top of the unit the body of the screw should be loose enough to remove with pliers.
Take it slow and you will be ok.
Take it slow and you will be ok.