GMC Troubleshooting Questions? Ask a Mechanic for Answers
There is a really good chance that the vehicle's Body Control Module was damaged.
The BCM will be damaged on this vehicle if it has power but no ground even momentarily (when the battery died, or when it was replaced).
Do you have a scan tool and multi-meter to be able to check communication with the BCM and grounds to the BCM?
Here is the location of the BCM to give you an idea of where you will be testing.
I just wanted to see if you needed any additional information. Also, I would appreciate a positive rating if I have been of any assistance. Thanks!