07 Laramie with Factory Nav/Radio almost useless

I just bought a 2007 1500 with Laramie package. Still learning everything it has. One thing that stands out is the factory navigation/radio/cd changer. It has controls on the back side of the steering wheel and infinity speakers. The problem is the big screen never turns on, I hear what sounds like a CD changer motor for a few seconds, and the only thing it will play is AM 600. I can turn it off and adjust the volume, but no other buttons on the unit work. The steering wheel controls cause the volume to go all the way up or down, but nothing in between. The previous own said it's been this way for a while, but said it was too expensive to replace. I see no physical damage, but who knows how or why it broke.
Suggestions on troubleshooting this one and replacement options are appreciated.

I replaced mine with a mygig with nav (used a coastaletech adapter). I like it better than the OEM 6disc nav that was in mine when I bought the truck.

That's common for the REC/NAV units. I've had to replace two and, thankfully, I had extended warranty on both vehicles. Dealer retail on those head units at the time was $2200!!!

Those units can be repaired and there are several online repair shops. Just google "REC Radio Repair". Some will take yours in trade and send you a freshly refurbed one.

Replacement options in addition to a MyGig OEM unit I'd recommend would be Alpine, Pioneer or Kenwood. If you go aftermarket, you'll need an interface harness to preserve steering wheel button function.

In my case, with the old MegaCab, I got a new OEM head unit under the warranty and replaced all the rest of the system (amp & speakers) and added a sub. It made for a much nicer sounding system.

Good luck!