does P0AA6 with 526 and 612 sub codes point to the HV battery being the issue 100%?

As you see in this drawing, 612 refers to any of the stuff on the internal-to-the-battery side of the system main relays.



A person who wanted to avoid unnecessary work would probably open up the battery case and inspect to find the cause.

Simply replacing the battery will probably fix the issue ... except, if the replacement battery is from Toyota, I believe it omits certain parts, which are to be swapped over from the old battery. If one of those parts was responsible for the code, then that would be a disappointing outcome.

 

No, with this trouble code it's not module voltages you're after, but current leakage paths to the metal chassis from somewhere among the components shown in the 612 area of that drawing.

If you look up the troubleshooting steps for P0AA6-612 in the repair manual, you'll see a sequence of steps involving disconnecting the internal cables from the system main relays so you can megohmmeter-test those in isolation, and the internal cables, and the battery ECU, before concluding the problem is in the stack of modules.

A megohmmeter is a specialized instrument and its use presents hazards. If you don't have one, and you think about buying one, you can search for threads here that will refer you to safety info you should study while waiting for the tool to arrive.

Sometimes, if only one leakage path has formed, you can get usable information by comparing voltage measurements from both ends of the pack to chassis ground. If you see an intermediate voltage, it nearly tells you where in the stack of modules the leak is.

But that only works if there's only one leakage path. With more than one, you will also see some intermediate voltage, but it will just be the voltage of the Thévenin-equivalent circuit made from all the modules, the leakage-path resistances, and your meter's impedance, and that won't have an easy interpretation in terms of where the leaks are.

 

When all this mess started in my '09 played with it a few minutes. And order the brand new battery from the dealer as mine was from '09 old is all get out use my front end off my battery computer and all that. Bolted it in never saw another light again till the brakes went out fix that now no lights just the PO420 can't nobody make that go away there's nothing in the path to replace.

 

I pretty much had the same exact code you do if I'm not mistaken and I did put the battery in myself and I did strip the battery down in my trunk as my core that you have to drop off when you pick up your new battery so I had another battery in the 2005 that was shot I took that out took the front end off the battery had it sitting in the trunk on top of the battery that was failing that's in my '09 drove all the way with the ice engine running at 36 mi to the gallon the Apex North Carolina where they handed me a new battery out of this big box that looks like it was refrigerated it was so protected but it wasn't refrigerated it was the thick box I set my core in that and took what was in that box and heaved it in my trunk. Went home added my front end which is the computer and the relays to the case that I just bought from the dealer and then drop that on the mounts and flip the switch and that was pretty much it I have mine mounts trimmed and cutting the funny way so that makes it so I can move the battery out of there in about six or eight minutes now

 

If replacing the battery made it go away, it was the same code. (At least, as long as we're talking about P0AA6 codes with some subcode.)

Notice that's the converse of "if you have the same code, replacing the battery will make it go away", and a statement doesn't logically imply its converse.

 

I had the p0AA6 code And after fiddle farting around on here getting all the sub codes in the snowflakes and the whatever I just decided to pull the battery pull the cover off while it's sitting in the hole and saw the disaster It looked like it had been played with before had bunches of writings on tops of different modules and what have you I knew somebody had done the dance before and wanted to just be rid of the nonsense. So I bought a new battery above is stated drop that in didn't even clear any codes just started the car with the battery and the metal case bolted down in the back just sitting there no trim back in yet nothing not doing that stuff three four times. I drove the car about 4 days with that trim removed so I could look and see everything add some leads for my Venice hybrid 300 volt charger and what have you. Then it went all back together I haven't even topped off charge that battery done anything since I put it in. A very interesting aside and something to note is the first 90 days of the new battery being in the car I never saw green on the MFD I also didn't see the magenta color either after 90 days I started seeing green almost daily and on almost every trip I make but I thought it was interesting about the first 90 to 120 days never saw green on the display and believe me I was looking at everything for those 90 to 120 days.