So, we called the local Nissan dealer to ask about this. The guy said that they had a Pathfinder do the same thing once. Here is the fix he suggested and that we used:
The latch mechanism is the problem. This is the thing made of mostly white plastic that is held into the door by three torx screws.
We carefully separated the window weatherstrip, inserted a long and beefy flathead screwdriver, setting the end on this piece of plastic. Three whacks with a hammer and it started to break into pieces.
We then had to fool around with the rods and such to get the door to unlatch.
Once the door was opened, it was a simple matter of replacing the part. We were able to save and reuse the actual electric actuator that makes power door locks what they are. That saved us $70 but it sometimes breaks to pieces with the rest of the assembly.
Total cost of repair was about $100 and an hour of time. I am sure a dealer would have charged 300 - 500 for the fix.
Thanks to all who responded to my original post.