Hello and welcome to Just Answer.
I have run into this problem quite a few times...I have always been able to get the liftgate open (eventually) by using the key to cycle the lock a few times.
Then try pressing the liftgate toward the vehicle (as if you are trying to close it more), then pull the latch all the way, then pull the liftgate open. Usually if you keep trying, it will open.
If you are successful, remove the trim panel and adjust the linkage to correct the problem.
If you are forced to remove the trim panel with the liftgate closed...you will probably have to break it to get it off.
That's common sense. The repetitive trys. Eventually opening. The key will not cycle the lock and eventually the acuator stopped working. Pushing, Pulling doesn't matter. Hundreds of tries over the past six months, many tries in a row. Hasn't helped, just trying to avoid the breaking and replacing part.