I fixed it!
After checking everything I could think of, I decided to look around for anything left unplugged. With the aid of an inspection mirror, I discovered a plug hiding between the stereo/climate control panel and the ashtray. Without the mirror, I was not able to see in there. This was left unplugged from the climate selector switch, which I also could not see as a result of the new, larger CD player above.
I must have inadvertently left it unlatched when I plugged it in initially.
I appreciate all of the suggestions!