'07 Prius Engine wont turn on after Catalytic Converter Replacement

I recently had my stolen catalytic converter replaced at a local mechanic. Less than 24 hours later my car engine will no longer kick on, the red triangle of death as well as every other warning light on the car popped up, it shows the battery is drained even though it was perfectly fine before, and the fuel indicator is flashing on and off but there is gas in the car.

I was told that the 12v battery needed replaced, so i took it to Auto Zone and they did say the battery is bad, so i spent $260 and bought a new one. Installed the new 12v and the car kicked on, drove forward a bit and then again wouldnt kick back on after i turned it off and back on.

I borrowed a little code reader and got a U0100 code on it. My dad drove an hour and messed with it and couldnt figure it out. He just came back today again with a bigger computer code reader and was messing with it for over an hour. Every thing has come back as being in working order/healthy on the car, the only thing that failed was the ABS. But the car engine needs to be running for that, my dad said.

He cant figure it out. He reset the car a few time, it would work for a second, but then not drive again and the codes are still up on the dashboard.

This Prius has done this one other time my dad said, and its when he replaced the wheel bearing. He had to have his friend come over with the computer he used today, and reset the Prius and then it was fine. This time its not working.

This is a 2007 Prius with 100k miles on it. Ive owned it for a month (literally got to drive it for 2 weeks before the cat was stolen), before i owned it my dad owned it and didnt drive it much at all, and the first owner was an elderly man where the car was maintained and in a garage. The Hybrid battery still had a little over half life left.

My dad honestly thinks its something really simple, but he said its beyond his knowledge for him to figure out. What is going on, and can I fix it myself?

 

i’m not sure what he did with the computer. but i replaced the EFI and fuses around it because they looked corroded/there maybe had been a spark. it fixed it and all the signals on the dashboard went away. so i started driving the few blocks towards home and it was working fine until about half way and then all the singnals popped up again and as i was pulling into a parking spot on my street the engine shut off again.

seems like the new fuse fixed it for a minute.

i was able to get power through the whole car by replacing the EFI fuse, but it didnt last long. The signals on the dashboard disappeared and I was able to drive my car home but by time i was pulling into a parking spot my car shut off again with every signal popping up on my dashboard.

 

i ended up getting it towed. They are thinking its the hybrid battery. I dont understand because everything was fine and i had half life left in it before the catalytic mess.

 

It was stolen on the 4th and i had it fixed on the 12th of august. I guess it was just a series of unfortunate events. Im making the decision to replace the hybrid battery since my Prius only has 100k, hopefully everything stays good on it for a while after this.