I have an O4 Chevy Cobalt flooded at work, up to about the headlights, but the water got down after 15 minutes. While the water was up, no key in car, the lights went on and the wipers and the radio. Later I've tried charging battery and nothing.
I hate to be the bearer of bad news but it's time to junk your Cobalt. Everything in that car is run by computers. If you get that much water, the whole system is shorted out. When it did that, the battery was still connected to the car and the computer still had power.
They all are going to be shorted out, and now they are going to go out pretty fast. When they go in that deep water, it's time to junk them. If you want to attempt to fix it, pull all the computers you can find out, bring them to your house, heat them with the hair drier and dry them up.
Maybe you'll get lucky and they start up again. You never know. But don't spend any serious money because it's probably ready for the junkyard now. When they get that deep, I'm assuming that it's old and you didn't have full coverage. If you have full coverage they will tow the car, but if you don't, don't spend a lot of money on it, because odds are that it's just ruined.
Have a car question? Get free advice from our top-rated mechanics.
Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%