Welcome to the forum!

Very nice 04 SS you got.

I have a 2004 also. The Onstar that came with the 2004 Montes are the analog system. Onstar stopped supporting the analog system over a year ago.

Unless the previous owner paid for the digital upgrade, you most likely still have the analog system in your car. It's the large black box in the trunk on the left side. Other members here have simply unplugged theirs and removed it to make more room in the trunk. Removing the old Onstar module (black box) won't affect your car at all. But the LED on the right side of your rearview mirror will go out.

As far as I know, removing the radio from your car shouldn't prevent your ignition key from working.

I had a problem once where my wheels were cranked all the way to one side when I parked. And the force of the wheel trying to return to the center position kept my key from turning. Once I played with the wheel and took the pressure off, the key turned.

Are you unable to turn the key? Or does it turn but won't start?

 

hmmmm. Tried to check if the wheels where cranked, but nothing. The key will not turn at all, just sits in the off position... Maybe when i removed the dash/ignition trim, i hit something?