I bought a gm delco stereo off ebay. The previous owner supplied the theft codes. They were not the correct ones. The stereo came out of a 2000 Pontiac Grand Prix. My car is a 2002 Grand Prix. I did similar to what you posted above with no luck. The stereo is permanently locked. I unhooked battery and it still is "inop". I don't know what to do. I can take it to a dealer, but I do not have the vin # off the original car. Can the dealer still unlock the stereo without the vin???