Grand Prix GXP locked in park and won't start.
 

Let me start with saying I'm new to the forum and am glad to see the vast knowledge that the members here have. Anyways, as the title states my gxp locked itself in park and won't turn over now. Key isn't stuck in the ignition, battery fully charged, no codes etc. All dash lights work just no power to solenoid on starter. Didn't seem to have any signs of issues before, just happened and can't move the car.

When you set the key the "RUN" which is one key rotation setting back from "TURN OVER" or "START"... your saying you can't hold the brake and take the car out of PARK while the key in the "RUN" setting???

Correct, starter won't engage either. Has a fresh battery also. Hasn't had any issues with anything except a code for evap and the slow fill tank. Preceeding the no start issue in the moments before it wouldn't go into drive, like it was physically locked out, then neutral, then it wouldn't come out of park. Shut the car off and hasn't rumbled to life since.

Internal Mode Switch possibly? I noticed that if you cycle the key multiple times, the small display in the console will show the car to either be in park or in 3rd.

I'm not a trans guy at all. But it sounds like it's stuck in third which is why it wont start. I suspect electrical is fine... something fakked in the trans.

Well that was my first instinct, but it had a properly working reverse before shutting the car off. It has a fresh reman trans with less than 500 miles on it. Just trying to eliminate anything other than that before sending it in for warranty work.