2019 XLE Starting Issues

I’m hoping someone more knowledgeable here has had this experience and can help point me in the correct direction.

I’ve got 148k miles on my 2019 Prius, brand new 12v battery and new brake sensor. The car will only start in “Maintenance Mode” and it won’t let me use cruise control and turns off the collision sensor.

If I try to start without maintenance mode, it only goes into accessory mode and will never actually start when I press the brake and push button. Horn, radio, ac, lights and all else work. My mechanic has a scanner that works for Toyotas and it only showed a brake sensor code (which is why I got a new sensor now). Despite the 12v battery being new (thought that was it first) it has died at least once more while at the mechanics place and he had to jump it to get it inside.

*Only damage it’s ever taken was my driver side mirror got sideswiped and I never fixed it (2 years ago).