I own a 1988 Chevrolet Camaro V6 and this issue started after my buddy and I had just replaced the starter. To test if it worked, I started the car while it was still on jacks, we heard the starter work, then I took the key out. We then lowered the car and tried to start the car, but this time the key wouldn't turn. We diagnosed multiple problems: nothing was stuck in the ignition cylinder (which had been recently replaced), the key goes in fine, moving the steering wheel does nothing. One thing we noticed was that while the car was in park, the steering wasn't locked which might have meant that it wasn't fully in park? But we still couldn't shift gears to move the shifter up more. Has anyone had this problem?

 

It may be that the steering wheel may have to be removed (again) to access and remove the lock cylinder (again) to verify whether the problem is the cylinder or linkage.

Does it help to try turning to the ACC position and then forward?

 

There's a cable that goes from the shifter to the steering column that rotates a "collar" on the column, which performs the Park interlock function, including both the key thing and the steering wheel lock. Sounds like maybe that isn't working right.

 

Update: We worked on the car today looking at both of these issues. The cable that went from the shifter was working as intended, but there was an issue with the ignition cylinder. When we took apart the steering wheel, the other side of the ignition switch (the gear side) had some sort of metal wire stuck that stopped the switch from turning over. We took that out and the key now turns over! Thanks for the help.