I currently have the same issues. most likely it's you LGM (liftgate control module). It will need to be replaced.
Also, to open your liftgate, get inside and there should be a circular cap in the middle below the window close to the floor. poop that open and there is a small lever inside. push/pull that and it will unlock. then you can open the liftgate from the outside again.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.