Had exactly the same issue one morning back in Feb. My Q3, registered in June 2019, suddenly was dead. Audi service came out and charged the battery, did a diagnostic check and found nothing. Later the Audi workshop did a full diagnostics and found nothing. The car has had no problems since.unlocked my 2019 Q3 This a.m., turned the key and got flashing lights and messages but no power to start car. One message about selecting drive or car would be locked. Since then absolutely no battery power so can’t lock the car. Any tips?