How I would do it personally. If the studs are already damaged - clamp vice grips to a stud, use a propane or map gas torch and focus heat at the base of the stud/case, apply counter-clockwise turning force to stud until it releases. Don't try to get it super hot and keep the flame focused mostly on the stud itself. You can put some permanent marker on the case around the hole, if it starts to fade stop applying heat as you are getting it way too hot. Remember, it only needs to reach 200 to 300 degrees.