Constant beep from center console Prius prime

I'm not aware of any "beeps" that are not associated with a message somewhere on the dash. Do you have any other devices plugged in to any 12V outlets? Maybe you can disconnect your 12V battery (negative terminal) for a few minutes and re-connect. That might clear it.

 

parking brake released? just checking...

 

Battery in smoke detector?
I’ve never heard an unknown beep or noise from car unless it was a kid toy hidden somewhere. Maybe you could post a short video recording.

 

https://www.thegreenhead.com/2008/12/annoy-a-tron-2.php

 

is there a dealer added alarm?

 

Oh, what a great memory you just triggered!!! I know this doesn't help @tersa984, but it was such a hoot.

My boss's boss, the engineering manager where I worked in Ohio was complaining about an occasional intermittent buzz he would hear in his office. It would go a few days and not do it and then it might do it several times in an hour. He had just about all of us electricians in his office off and on for weeks looking for it, but it wouldn't do it when one of us was in there. Finally, he noticed that there was a 480-120V transformer on the other side of the wall he shared with the machine shop. He was convinced that that was the source of the noise and told us to swap it out whether we agreed or not, so one of the guys made the change.

Guess what. An hour later, the buzz came back. A few days later, the company nurse was in his office talking to him and the buzz came again. She opened his center desk drawer and there was his pager (remember those?) dancing around the drawer going "buzzzzz ... buzzzz ... buzzzzz." He should have sworn her to secrecy!! We sure had a ton of fun with that in the electric shop.

As for the mystery buzzer that even buzzes after shutting off the car, that sounds like something that needs dealer attention. I can't find anything in my manual that fits the description.