Dash Lights Red Brake and Yellow ABS On

First, how old is that 12-V battery?

Get the codes. Jumper terminals 4&13 of the DLC3. (CG and TC). Count the flashes. There are other threads about this here, and it's described in your repair manual.

 

A lot of code readers, even generic ones, should retrieve codes from the Prius brake system—after all, lots of cars, even generic ones, have brakes. Usually it's the more esoteric bits of the Prius that the generic tools won't read codes for.

But in any case, any time the reading tool at hand isn't cooperating for whatever reason, the brake system does have the fallback option to blink out two-digit codes on the dash lights, as mentioned above. Handy, because you can pretty much get a short wire somewhere no matter where you are when you need it, and it takes any questions about your code reader out of the picture.

On the other hand, the two-digit blink codes give you less detail than a Prius-suitable reader would. Better than no info at all though.