Guarantee doesn't include cases where the knucklehead before you used the wrong screwdriver and rounded the crap out of the screw head For those cases, there's

Guarantee doesn't include cases where the knucklehead before you used the wrong screwdriver and rounded the crap out of the screw head For those cases, there's the manual impact driver. Hand-held, whack the end of it with a hammer and it drives the Phillips/whatever bit into the fastener while giving it a little twist. A couple of whacks will remove the most stubborn screw. Or it will tear the head off. Those are the only two outcomes I've ever seen, it never just sits and spins in the rounded slots.