[phewop118]

1st, try to disconnect the radio by pulling the harness behind it (I suppose pulling the fuse would be the equivalent). If that doesn't work, I'd just take it to the dealer to get it replaced if it's under warranty. GM has had an arseload of problems with these radios, though it is hit or miss if you have a bad one. I went through 3 in the first 6 months of my 05. If it is no longer under warranty, you can get a replacement cheap on ebay and have the dealer unlock it.