I hope someone with a more recent model can help..... but the symptoms are the same as my Lumina APV minivan side door.
About every 5 years they failed the same way, the inside lock/unlock lever getting almost numb... the electric lock-unlock was muted.
A long pushrod from the lock-unlock lever ran through a plastic guide block... it looked like a nylon block... and it seem to be lubricated with tree sap! A thorough cleaning, and it would be like new for 5 years.... then, new treesap showed up and it would stick again. Perhaps this goop was coming out of the plastic block.... who knows??
How to get it open?? It would open on a hot day, if the "treeSap" side door was parked facing the sun.... getting hot enough to thin the goop.
No idea if GM was still using this mechanical design 10 years later though.