Audio Systems: ac delco cd player, ac delco, chevrolet dealer

Question
I am trying to put my radio back into my 1996 impala and when i hook  up the radio the  display come up lock.How can I unlock the radio?

Answer
what happened is the anti theft circuits started. only thing you can do is go to local chevrolet dealer, with your registration to prove you didn't steal it and they will give you the button sequence to unlock it. since it's 11 years old, they might give you the sequence over the phone, but still have vin number and proof of ownership handy..