I'm in the process of replacing my IMA battery, and have been unable to remove the grounding bolt of all things. The metal the nut is attached to is very flimsy and the nut has a proprietary non-symmetrical shape that's just above 10mm and below 11mm. This 12 year old bolt has never been removed before and is a bit seized on there. I've already tried WD40 and just applied some bicycle chain lubcricant/cleaner and am waiting for that to penetrate.

Any suggestions for how I can remove this bolt? Kind of dead in the water here without being able to remove this grounding bolt.