Rear hatch won't open

Actuator connector was never re-wired. After I install actuator, I just plug in actuator connector in it and tested.

In other words. I unplug the actuator, replace with new one, plug-in actuator connector. I did not connect any wires or change the polarities at any point of time.

My electric door locks function properly, byut when I lock them with the electronic key fob, the rear hatch door (I don't have "barn door" rear access), does not lock. I have been told it is mostlikely the "activator". I am very adept with tools, but before tacking this, I'd like to know if there are any special "tricks", pitfalls, etc. Where is it and how do I access it the easiest way? Can I just buy the activator from GMC and replace it myself, or is it wiser to just burn a day and drive it to the GMC service center.

Thanks for your help.

A few weeks ago my charger broke and a small metal piece fell into my lighter port causing some fuses to blow. I checked and changed the one for the lighter, now I cannot locate where the fuse is for my rear hatch or four wheel drive. My husband is in prison and I need Hungary working before the snow comes. Please help