As long as your car has gas, the computer would just tell the ICE to run and the car should start fine. I don't know why your charge went down so fast (you weren't blasting AC in the middle of a car wash...right?). I have had my NAH in many car washes and it was never a problem. I also don't know why your engine didn't come on in neutral. I'm pretty sure mine has.

I know I have been stuck in many NJ traffic jams where my charge has gone to bottom and the engine has come on only to have the charge go back down several times in a row.

The warning lights are not a great sign. Maybe you should have Nissan take a look.