2007 Prius Inverter Issue

Hello everyone! I have been stalking Prius Chat since 2017 when I got my first 2005 Prius, but I just now decided to officially join!

I'm hoping that someone can help me out. I currently have a 2007 Prius that recently Red Triangle of Death'd on me. Took it to the shop and after spending ~$600 on towing, diagnostics, and a new 12v battery, I ended up with a P09A4 - 555 Code from the dealership. They wanted ~$5k to replace. No thank you.

I got a replacement inverter from a junkyard and swapped it out. when I powered it on and tried to start it up, I still have the Red Triangle of Death. I plugged in my OBDII scanner, but there are no codes to be read.

A few details that might be useful:

-The inverter coolant pump went out on me back in late 2019, but I replaced that and have had no issues with the Prius up until now.
-When the Red Triangle of Death originally turned on for me about a week ago, it was while I was quickly accelerating. When this happened, the car went into a semi usable state and I was able to park it. After that, it would power on and drive for a small amount of time. I tried to get it to the dealership while it was in this state, but I assume the main battery lost all it's juice and it completely shut down on me (accelerator wouldn't do anything and it would only go into Park and Neutral).

Does anybody have any suggestions on what might be the problem, or does anybody know of a reliable source where I can purchase Toyota Techstream & a VCI cable combo?

Also, I know it's a long shot, but if there happens to be anybody in the Greenville SC area that has code-reading capabilities, I would be super appreciative if they could help me out.

Any help/advice on this issue is greatly appreciated!

 

Forgot a bit of info! I just recently had to replace the Driver's Side front wheel bearing. Don't know if that pertains to this issue at all, but I thought I'd put it out there.

 

Voltage at the front jump point reads 12V.

I’ve unplugged the 12V battery at the back of the car a few different times, and it doesn’t appear to have any positive effects

 

Update time!

So I realized that after I replaced the inverter, I failed to press down on the Service Safety Plug when I reinstalled it *Facepalm*. I plugged it in properly today, and when I started the car, the engine actually turned on! However, the Red Triangle of Death is still present and it is in limp mode.

I got my hands on Techstream and was able to read the error codes:

Hybrid Control:
P0A0D
HV Battery:
P0A7F (Hybrid Battery Pack Deterioration) & P0A80 (Replace Hybrid Battery Pack)

Is this a "simple" issue of the battery needing to be replaced now? Was the inverter error linked to this, or is it possible that these two, separate issues happened to happen at the same time?

Thank you again for any advice!

 

I checked it again today:

Car off & Headlights off ~12.44 Volts
Car off & Headlights on ~ 11.61 Volts
Car off & Headlights/High Beams on ~11.95 to 12.00 Volts