U029A obd code 2010

Vehicle is a 2010 Prius level 2. Read codes off a Carista obd module and their licensed software. Has been running perfect (2 years) all up until today after I had ceramic film installed on my front windshield to cut down on the FL heat. Got in my car to leave but yellow triangle and "check hybrid system" lit up on the display. Wouldn't even turn on the i.c.e. as I checked for codes. After a few minutes, the engine did turn on, but still showed error and I was able to switch it into forward and reverse from park. All other electronics worked, but no a/c though as it only blew hot air, no compressor noise either as I'm sure that runs off the hv battery. Limped it home with defrost on full blast on back roads with as few stops as possible so I could carry momentum and not hit all the lights, legally of course.

The only electrical plug that was disconnected was the auto dimming mirror as far as I know when asked. The installer said he didn't use a lot of liquid, was careful, and covered the cluster as he worked inside the car. Possible liquid short? Any control modules or sensors that would be located on the interior engine bay firewall that could have shorted? Could the car being in accessory mode drain the 12v battery down to where it wouldn't talk to the hv battery control modules causing said fault? I replaced the 12v battery about a year ago with an Optima unit.

Looking for any extra places to check that would involve the U029A obd code. Any specific interior fuses or modules to check before I go testing everything blindly?

I have disconnected the 12v battery for an hour, the HV orange connector, and checked all engine bay fuses to see if it would self reset (old school procedure of holding brakes for 15 seconds to clear all voltage as well), still shows error. Have not checked interior fuses as of yet. Have 12v battery that came with car on smart charger and will replace to see if anything changes.

Hoping it's nothing serious, and maybe something just needs to be dried out or replaced. Any help is appreciated. Not a certified mechanic, but I know my way around a vehicle.

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Fresh 12v battery fixed the problem. Only possibility was car was left in ACC mode as windshield was getting film put on.

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It was about a 2 hour job. My guess is it wasn't turned completely off, radio on, a/c fan running more than likely without being in "run" mode. I had a spare factory battery I installed when I got home and recharged the Optima that was in it.. Has been fine ever since, minus the $2700 bill to replace the brake accumulator and master cylinder at Toyota because I don't mess with abs systems. Kid didn't know hybrids I'm guessing, informed and educated him, wasn't mad at all. They were prepared to pay to get it fixed if need be.

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