Could be the GM, you never know. The only thing that made me verify that the actuator was going bad was a relatively loud grinding/squeeking noise just before it stopped working at all.
There's a temp solution that *might* do the trick. Take the door lock pin out, take a can of WD40 with the straw attached on it, put the straw in parallel with the door pin shaft, insert it as down as possible and spray a generous amount of WD40. The WD40 will follow the door lock shaft and eventually get into the actuator. Sometimes it will revive it and give it another year, sometimes it won't do $hit. Better to leave the door open to have the extra WD40 drain on the floor and not on the seals. Should see results if any within a day.
I did this trick and the car will lock the door but will fail to unlock it. I am still going to change the actuator, reason I haven't posted anything yet is because the dealership is closed for holidays for this week. They will be open on monday 25th.