HELP! I have a 2004 Buick Regal LS with a Delco RDS radio. I want to know how to change the battery without the radio locking up on me. or I want to know how to unlock the radio myself. I heard the dealer can unlock it for $50-$100. I just want to save some $$$. Any help will be appriciated.

I doubt it will lock up, they only lock up (from personal experience) when they are disconnected from the harness/removed from vehicle. I might be wrong but if it does it without being removed from the vehicle, you have other issues with the RDS and Buicks security.