So, to introduce myself, I am a previous Mini Owner back in the fold. I had a very cute R55 that I sold but still had that itch.
Yesterday I purchased an R57 I found a couple weeks ago after some negotiations. It has a bad N18 but can still move under its own power so I can get it in the garage for the surgery.

Here is my problem. The battery was toast at some point and the Brain Surgeon installed a temporary battery from his tractor. (yes, for real) I didn't like it but it worked to get the car home (via AAA)
So just checked the battery and noticed why the tractor battery was also toast and not holding a charge. The POS terminal makes contact with the Hood when closed. Cowl cover has been removed/

So what do you think has been fried? I did an OBD scan and got a bunch of codes, many of which I expected but I am not sure of the modules that could be fried.
Codes are MIsfires, "Lost communication with Engine" stuff like that.

So to the collective, How bad do you think it is??

Thanks in advance, Dan