Hello - pretty new to this group but I've run across an odd issue that I can't seem to come up with a solution to. I have a 2012 G37x with ~90k miles. I noticed some interior leaking that was forcing me to regularly vacuum out water this summer (we got crazy rain this summer). I took my car to be inspected and my mechanic told me there was a warning light that he couldn't resolve and the dealership would have to look at.

Sure enough, within a week or two, almost all of my lights came on my dash. I didn't notice any changes in performance but clearly there was a problem and my guess was that water had gotten through to some part of the electrical system and something needed to be reset. I took the car to the dealership and they told me I definitely had a leak in the interior and that it was time for a new wheel bearing and sensor (that could have been throwing an error). On retrieving my vehicle from the dealership, I made it maybe 100 meters and the car began to stall and the transmission wasn't catching. It would rev but not pull. Sometimes it wouldn't shift. None of this was happening prior to the car seeing the dealership. The dealership claims they did two things: investigate the leak (which I had fixed outside of the dealership) and update the ECM (not the TCM).

My car entered the dealership with zero problems with the transmission and now it's basically undriveable. I've been searching for things the dealership could have done inadvertently to create the transmission problem, but I can't find a connection between ECM updates and/or tearing into the interior to look at a leak cause. The dealership took my functional car and made it useless and claims they don't know how they could have caused the issue, so any help would be super appreciated.