So I just spent all day failing to remove the battery in my Mini, as removing the long bolt which holds it down has proven to be a massive pain.

From what I can gather, the captive nut, which should be on the underside of the tray has sheered off, probably due to corrosion damaging the weld. Consequently, when I spin the bolt it doesn't come out as the nut is spinning with it. I tried pulling straight up hard when twisting, pulling at an angle, levering it with a flathead for extra upward pressure, and I tried gently shaking it whilst unscrewing. But it won't budge.

Eventually, I decided to try hitting the bolt hard in an attempt to break the small collar, which might have allowed me to move the bracket out the way to remove the battery. Unfortunately this just ended up bending the bolt (in hindsight not the best idea).

On top of this, it appears a previous owner/someone who worked on the car, has neglected to screw the tray-securing-bolt all the way in (as seen in the video). This means, even if I didn't have an issue undoing the bolt, the bracket would be stuck anyway!

So I come to you for help!

If you have any ideas on how I might get the bracket out, I would greatly appreciate it, any method necessary, though ideally not damaging the tray.. Or if you know how I might be able to access it from underneath - but from the looks of it, it's quite enclosed - so if you have any knowledge, please inform me.

**Extra Details:**
- The gap between the battery and its housing is very narrow (even my palm is too thick to reach down), so I doubt any tools will fit
- A narrow crow bar might fit, but there aren't really any good areas to get leverage on from what I can see.
- I'm fairly sure the "captive" nut is not a hex head, it is round. Therefore to hold it must be grips not a socket/spanner.

**My ideas so far:**
- Use a breaker bar over the bolt to bend it side to side until it snaps, hopefully between the collar and the nut
- A small hack saw to cut below the collar - very doubtful about this, the gap between the collar and the bracket is tiny, there are several things in the way etc. 

Thanks in advance.

Car Details: 2009 Mini Cooper R56 Non-S (N12 Engine), RHD

Can't remove my battery - The hold down bolt just spins!