Depending on your access, you can dremel a screw driver slot, tig weld a little stem with handle, drop a hex nut over the stem of the bolt and spot weld the nut to it, using a guide bushing drill a small hole then tap a torx screw driver in the hole. Most likely it's still loose and hasn't bottomed out in the hole, even a sharp punch can coax it out, or needle nose pliers.