After a break for the holiday; I gave it a few more attempts today. Was able to get a socket hammered on better than before....but ended up only mutilating things more. Got my endoscope in there to snag a few pics. The damage is impressive, lolz.







At this point I'm going to grab a cold chisel and try to spin it per your suggestion Andrew. Can't hurt to try! If I can't spin it, then I'll try and shear it off and hope I can get some pliers in there to spin the screw shaft more easily than my attempts to do the same with what remains of this bolt.

It's not donation material yet, but it's edging closer and closer....