Do not assume you have blown a head gasket. Cranking the A4 excessively w/o starting can result in water getting into the cylinders. You did the right thing by getting the water out and getting MMO into the cylinders. Hopefully you cranked it over to get the MMO to your rings.
Run a compression check.
If your engine was running fine the last time before you shut it down I am going to bet is is still OK. Head gaskets don''t blow just sitting around and waiting.
After you get it going and check the compression, keep your eye on things. Check the oil to look for signs of water. I am putting my money on your engine is OK and you just cranked it too long.
I think what happens is that as you you crank, exhaust
water backs up because the engine is not kicking it out with enough force and it ends up backing into your cylinders.
One can install a drain valve at a low point in the exhaust
system downstream from where the water enters. When the engine is being stubborn, that valve can be opened to prevent the exhaust
system from filling up with water.