Hi i got my 2015 q40 and I've been tuning it up spark plugs fluids throttle body clean valve cover gaskets.
put it all back together drove it for a couple hours no issues.

then i started getting a bit of fluctuations in the idle drove it and idle went up and settled at 1100. did idle relearn with my xtool and it settled at 650.
went to go get gas and the car started revving like crazy and put me on the side of the road. when i start it just revs wildly if i put it in reverse car instantly died.

so i seen some posts where water from sun roof leak may be an issue so i looked in my floor board and it was wet. fantastic. then i took the ecu and bcm loose there was a bit of water around the ecu harness and corrosion in one of the bcm connecter pins. i tried cleaning then up drying them out half assed. didnt see water in the unit themselves just around the connectors. ill try to attatch some images. any help would be greatly appreciated.