Had to get my car towed because a rock chipped the radiator;
Used the head unit while waiting for the truck, that was fine. After we arrived at the shop, the truck driver let the car down and tried to crank it for about 2 minutes (battery had evidently run flat). Eventually, it wouldn't start so he jumped it and drove it into the shop.
The shop replaced the radiator and everything is fine but now the head unit doesn't start.
It's an aftermarket system with a screen and doesn't turn on at all or do anything noticeable - what steps should I take to fix this?
The car is an '06 tdi passat.