Interior lights go off when closing the door on my 04 Blazer but, the radio won't go off. I have to turn it off manually. It is the stock radio. I just bought this Blazer, so I'm not that used to it yet. Please help before my wife kills my battery. LOL

 

Pull the factory stereo out and inspect the wiring harness. It sounds to me like someone cut the harness to install an aftermarket unit and tried to wire the factory one back in when they went to sell the truck.

There's not typically any other reason for those kinds of issues to happen with the factory stereo if nothing has ever been tampered with.