Red Triangle keeps coming on intermittently

Translated: The tech is not competent enough to find an open wire that is well documented by Toyota.

Obtaining the drawings from the Toyota TIS system would be the first thing an experienced tech would do. He would want to understand the circuit prior attempting anything. The TIS system requires paid access ($25 for two days) and some experience to navigate and ultimately understand the drawings.

TIS System

Jumping 12v past a suspected open in a wire harness by an untrained person could cause even more problems. Ecus could be permanently damaged guaranteeing a junk yard exit for the car.

P Lock C2310 Fix Fixed Solved Solution | PriusChatIt

Right now the right tech might fix it for one or two hours labor. Unfortunately dealer mechanics are not the best resource these days.

I would find an independent automotive diagnostician like Ivan at Pine Hollow diagnostics or a similar recommended shop near you.
Pine Hollow Auto Diagnostics - Home

 

I don't know if this would fit under the fuse cover, but there are little fuse holders which are already tapped that can go into the slot instead of the fuse, and then the fuse is plugged into this new part. Here is a picture of one (this particular one holds two fuses, you don't need that, just one fuse slot, and in this one the fuse goes in sideways):

https://www.napaonline.com/en/p/NW_785135

Pull the fuse and plug this tap in. Don't install the fuse yet. Turn on the car (expect error codes/warning lights as that circuit will not be powered). Check the voltage in the crimp with respect to ground (bare metal on the car frame, usually a bolt head). If you see +12V turn the tap around. You should now see no voltage (probably 0V, but it might be wandering around because the wire is dangling in space and its voltage is more "undefined" than "zero"). Now put the fuse in, and that tap wire should read +12V. The wire is now tapped in downstream from the fuse, and anything attached to that wire will be protected by the fuse.

The other way to do this is to get underneath the fuse box and find where the wire for that circuit comes out, and then use a tap like this (there are many varieties of taps, this is just one type):

Posi-Tap- No Crimp Tap

on the wire.