They should just start putting dash cams on all cars from the factory. I've seen too many times lately of people changing their story after the accident. Plus now that cops don't come to the scene unless there is an injury, it's much easier to play he said she said after the fact.
yeah... two odd things
1) that the battery was completely dead. I wonder if there is some kind of short or draw?
2) The ground you had to remove just so happens to be the one controlling all the functions that aren't working.
I'll be curious to see what you end up finding!