GMC Repair: 2004 Yukon Denali XL wont start, negative battery cable, 2004 yukon denali

Question
The family and I went to the mall tonight.  Came back to the Denali and she would not start.  We are the sole owners and have taken VERY good care of this excellent vehicle.  I called OnStar; but the vehicle cranked up after 40 minutes of wait time.  On the way home, noticed that VERY hot air blows from driver's side; cool air from PAX side when A/C is on.  Got home, parked in garage; re-tried to start the SUV; no joy.  My pops retired from Saginaw Steering Gear; thus I am a HUGE GM fan.  Should I pull fuses; reset via battery terminal removal; or just suck it up and take it to the dealership for computer analysis (provided I can get 'er to start).  

UPDATE: I took off and re-attached the negative battery cable; fixed the aircon problem.  However, I had to get a boost to charge the battery.  After driving the vehicle for 40 minutes, I backed into the garage, turned it off.  The vehicle would not start immediately afterwards... only clicking noises.  Ideas?

Answer
Hi
Sounds like a classic battery failure.
I am SURE it will just be a battery. You can take the battery out, and take it to a parts chain store (auto Zone, Napa, etc...) and have it checked. After replacing battery, take the truck to the same store, and have the charging system double checked, just to be safe.
I hope this helps
Pawl.