If you could take the door off and use some type of pulling system to pull the top of the door back in. It shouldn't be that hard to bend the top of the door. Maybe lay it down on the floor on the outer door skin and then block it to the ceiling of your shop using some lumber or something and then put a jack on the bent area and start bending it back to shape. I don't know but it should work to push it back into shape. Good luck, tell us how it turns out.
