Well, the first thing to do is to yank the battery out of the car and take it to Autozone and get a replacement, and buy one of those battery post wire brush thingys.
When you get home, clean up the battery cable clamps and put the new battery in.

NOW, start the car and see what you have. I'd ALMOST bet you will have everything good, cept the BAS light will still be on.
Do the steering angle alignment thing and see if that takes care of it.

Do this:
(I would do this on grass or dirt, not pavement)
If the power supply was interrupted (battery disconnected or discharged), the BAS/ESP malfunction indicator light may be illuminated with the engine running. To re-synchronize the ESP, and cancel the malfunction indicator light, the steering angle sensor will need to be recalibrated.

1. Turn the ignition switch to the ON/RUN position.
2. Rotate the steering wheel to the center position.
3. Rotate the steering wheel completely to the left, and then rotate the steering wheel completely to the right.
4. Bring the steering wheel back to the center position.
5. The BAS/ESP malfunction indicator light will go out.

If the BAS/ESP malfunction indicator light is still illuminated, the vehicle should be serviced at an authorized
dealer check back with us! (If you take the car to the dealer for any reason, you are banned from Crossfireforum for life. )