Rear Hatch Lock / Sensor

Howdy. First post on the forum, but I've used a few of the threads here to solve other minor quibbles with the otherwise incredible Prius.

A few months ago, the rear hatch of my 2010 Gen 3 Prius decided that it was no longer going to open. The rear hatch will not respond to the proximity sensor / fob, nor does it open to the actual trunk release button when pressed while unlocked.

The key fob works on both the front driver and passenger door. The fob battery is new. The low voltage battery was replaced a little over a year ago.

So, what parts do I need to replace? Is the whole actuator toast? Or is it just the sensor?

As is, I have a piece of 550 parachute cord running to the mechanism, with the tail coming up into the rear trunk area. I have to crawl into the back to yank on the cord and release the lock, then headbutt the gate open unless someone is outside to pull it up.

 

Nobody?

This hasn't happened to anyone else?

I'm assuming that it's just the switch. I'll start there and report back.