take it out
once you get the panel and plastic film peeled back unhook the one rod from the push/pull tab.
pop out the wire holder so you have some slack wire to remove the lock. pop the rod out from the plastic guide. go to unscrew the 3 black bolts that holds the lock inside the door. unhook the wire harness and remove the lock.
I'm pretty sure your worm gear, which is made of plastic, has snapped within the actuator device. look it up on this forum. there is a pic of the broken gear. that is what is making the grinding noise.
you must first remove the actuator from the lock mechanism. then remove the actuator's cover to reveal the worm gear. be careful the small springs might pop out when you go to remove the cover. wear safety glasses if your worried the springs will jump out and poke you in the eye...
clean the worm gear around the break. super glue it back together. be sure to be as accurate as possible when joining the broken parts so that the threads are lined up and try not to get extra glue on the gear track. Else you may need to chip it out after the glue sets.
put it all back together... it's probably stronger than before. so just pray the other lock actuators don't break or you'll be doing this again. Unless you don't mind getting ripped off at the dealer, for $80, just for the part not including the labor.