A5 Quattro 2ltr 225 2015 My wife stalled the car last night trying to revers up hill into parking space. When trying to restart the car as start stop didn't work? the lights and dash lights went out. Put in neutral, hand brake on, Clutch in push key lights out again. 3x same result. Took key out reinserted same another 2x trying to start, then on 3rd attempt she started as normal. I would normally say battery or stuck solenoid but she turned over perfect, eventually. Had just come back from a long 2 1/2 hour drive so battery fully charged. Will be contacting Audi as only had car one week just like your thought on the problem.