Hooked battery backward, car won't start

[Katosha]

Yes. It looks just like that

[CoryM]

Originally Posted by Katosha

Yes. It looks just like that

That's..... not good. The odds of your ECU being fried are pretty high. If this was in my shop, next I would: check if a Scanner would communicate, check all fuses, check for ignition spark, and check for 5V reference. Then, depending on what I found, do a pin-out on the ECU. Honestly, I would guess at this point it is best for you to use a professional. Especially since if the ECU is required, it will need to be programmed by Toyota (or at least someone with the proper scanner). Trying to guide someone through the diag process would be very difficult and/or impossible.

I should also mention it is possible there are other components damaged: If it's enough to pop the ECU, it can kill other chips too. This could get expensive to the point you may want to see if your car insurance would cover it. I once worked on a Suburban where it was incorrectly jump-started: It fried every single chip on the truck. From the ECU to the taillight modules. We got it drivable with an ECU and antitheft stuff etc, but he took the truck away still needing a lot of money spent on all the other modules/chips. The Yaris is much simpler, so it won't be as bad as that but still not good for the bank account.