Dead battery 2014 GMC Terrain

Happen to have access to a multimeter that can measure milliamps? Disconnect negative cable and use multimeter to complete the circuit. Sounds like you're looking for a major parasitic drain. Having the multimeter set to measure up to 200 ma see how much voltage is used while car is off. Anything over 50 is considered parasitic. Pull fuses 1 at a time and check to see if the current has decreased. That will tell you what circuit(s) to look into

I had this same problem. The dealer kept my car, hooked it up, couldn’t find anything wrong. I went through a couple of batteries. I was finally told my Bluetooth was staying on and running the battery down. I had to turn off Bluetooth, completely take my number out because it would turn back on! I can’t use my phone through the car at all! I also always turn my radio off!! I was told by a mechanic from an outside company that GMC knows this. I called them and they wouldn’t admit there was a problem.