08 Prius Touring engine is not starting/Ready Mode. I have tried a lot of solutions

Hello! Could really use some help with my wife's Prius. I'm trying to do as much as I can ( I'm a DIY guy) before having to take it to a shop.

2008 Prius Touring 180k miles.

Prius engine is not starting, it's not going into Ready Mode. I've scoured the internet for a solution with no luck. For the past 6 months my wife has had a problem with it not starting up on the first few tries (sometimes first 10 tries) but eventually it starts. It's never turned off while driving. It goes into accessory mode just fine, lights aren't dim.

What I've done:
It has a new 12 volt Battery from the dealer. Key fob has a new battery. Checked all fuses. Used an ODB2 reader and there were no codes. Checked the brake light switch ( I don't believe it's that). I've disconnected/reconnected the 12v battery. I've also disconnected the 12v and the HV battery and reconnected it, that time it turn on once, but I also got the Red Triangle. The triangle went away after a few minutes but it deterred me from trying that again haha. HV battery is half full at the moment, so my next step would be buying a Bluetooth OBD w/ the Dr. Prius app to check the HV battery.

My other thoughts are it could possibly be either the ECU module or something to do with the brakes not registering...so it doesn't turn on. There is and has always been a weird constant chirp whenever the brakes are pressed down, which I've read is a possible Vacuum Booster Leak. Although, I can hear it pressurizing after hitting the brakes. They feel normal, as in they don't hit the floor and aren't weak.
Any help is much appreciated, thank you

 

Yes all lights on the dash come on normally. It's the weirdest thing I've disconnected and reconnected the 12v battery multiple times and it does not start afterwards.

 

I just checked and when I press the brakes the brake lights do not come on!!! Grabbing a Brake Switch tomorrow. Hopefully that works, thank you everyone!

 

So my brake light switch was the wrong part and had to reorder a new one. In the meantime I decided to swap out some fuses. None of fuses were blown but weirdly enough every fuse located under the dash had as scorch marks. I swapped them all out, then my Prius turned on (Ready Mode)! It was finicky and started consistently for about 2-3 days and has now gone back to not starting.... whenever I see the brake light turn on it does start. Sadly, hasn't started all day though. Brake light switch??

 

12V battery is reading at 12.33v. 12v battery is less than a year old and is also the AGM battery made for a Prius