probably because it wanted the radio code when you refitted the battery and the code has since been entered incorrectly. Wait will stay on now for anytime between 30 mins to 24 hrs and then may offer you the chance to put the correct code in .
If you dont have the code or it still wont work then take the radio out and put it in the bin.
Either replace with a sensible radio or sing along when driving instead lol
I might be able to get the code for you for free if you dont have it , email me stuart200sx@mail.com
So there. That's it ....i think
stupid stuart, November 2008