2010 Gen Three Prius Trunk Lock Intermittent Failure

Have you tried some lubrication? Also, you might want to see if something has fallen in there and is causing interference in there.

 

What price for genuine drove you to Amazon. I’m seeing mostly $172~ CDN ($126 USD) here:

https://www.amayama.com/en/genuine-catalogs/epc/toyota-usa/prius/ZVW30L/13501/body/6709

see what it is with shipping for you. I’ve used them and so far shipping was the only extra, no sales tax or import duty. Do verify with your frame number or VIN.

 

What goes on with the hatch is different from what goes on with the doors.

In the doors, there's a mechanical difference between locked and unlocked. The actuator physically moves from locked to unlocked when you press the fob button. Then when you pull the door handle, it opens because it's unlocked.

The hatch is different. Its electric actuator releases right at the moment you press the hatch release button. Or it doesn't, if the Body ECU considers the hatch to be locked. There isn't anything mechanical happening to the hatch when you press the fob unlock button; the only change is the Body ECU now thinking "ok, I'm unlocked" instead of "go away, I'm locked".

This might help with diagnosis a little, because with the doors you can have a situation where the actuator isn't always mechanically moving from locked to unlocked when you press the fob button, and that'll often be the door actuator.

But the hatch's electric actuator operates just at the moment you release the hatch, every time. Of course it should never, ever open when the body ECU considers the hatch locked, and it should open on every attempt when the ECU considers it unlocked.

In a state where you know the ECU considers the car unlocked (this is probably in the viewable live data), if the hatch doesn't open reliably every time you press the hatch release, that could be an actuator problem. But if the symptoms seem more as if the ECU isn't always going to unlocked state when you use the fob button, the issue is more likely in the wireless key system.