I just bought a used '06...and it has so many problems!

What's the question?

You bought a car that someone was flipping. That had been in at least 1 accident in the front. That had a bad hybrid battery, why else would the flipper be in there. Had a band-aid fix of whack-a-mole applied to the battery. And obviously not well based on the codes. All of these things seem like they would be evident in a pre-purchase mechanic inspection. I'd wager they'd be evident just on the drive to the mechanic for a pre-purchase inspection without even needing to spend any money on an inspection itself.

You've already bought the car, so it's your problem now. But it may just be a writeoff at this point.

You definitely got at least 2 problems going on. 1 in the HV battery and 1 in/on/around the engine itself.

Since this backyard mechanic was recently in the HV battery, I'd start there first. Take it completely out, redo the entire thing. Take all the modules out. Balance and charge them all. Put them all back in with the proper torque specs. Do not just eyeball it and say "it looks fine". Clean the bus-bars. Clean corrosion. Replace the most likely other bad modules at a minimum if you want to keep playing this whack-a-mole game. Hope that by fixing the battery correctly P3000,P3024,C1241,C1310 all go away. Then you still have some issues in the engine potentially. But that's a whole different problem and I'd start with the easier one to solve or decide if it's junk. If the HV ECU and Inverter are really toast, then you bought a paperweight. Good to know that upfront with only some more sweat equity invested.

 

What’s your resting 12 volt battery voltage?
Hope you didn’t pay very much for the car.

 

Spend a couple thousand dollars to fix it and you should have a pretty nice vehicle.

What you describe is not I surmountable.
Hopefully the guy only charged you a couple hundred for it.

 

Lucky for him he has a parts car.

 

Put an ammeter on the battery, read the baseline draw.

Then pull fuses out one at a time until the drain vanishes. That tells you which branch circuit is pulling you down, and you can narrow it down from there.

Shortcut: Some smart key systems will cause extra drain to the vehicle battery if the key is stored in or near the car- the onboard computer gets bad radio reads of the key codes and goes into a retry loop (which consumes power) instead of just going to sleep. To verify this, put all of the keys in a metal box for a while to prevent communication with the car. Ammeter helps for this test too.

 

I got one junkie high mileage, no caring, 2007 Prius as well 2 weeks ago in limp mode, I was lucky that I got a used hybrid battery, I replaced it using youtube video plus problem of 12 volts battery low voltage, Hybrid battery's orange safety lock not locked Else, it is working fine now. Of course, It has many minor problems waiting for me to fix them.
If 12 volts battery is weak, It showed many strange error messages. I charged my battery with charger.
If order to save 12V energy, I turn off SKS because SKS fob is dead.

 

My car is very high mileage, I am just lucky to find a used Hybrid battery and it is main problem, However, It has many other problem, Like FOB is not working, rear car multiple leaking badly. it is more work than I think.
I do not know mechanic but I was electronic tech doing thousand of repairs in my young year.
Once you check with that 12V battery, If it is fine. you might move on Hybrid battery.
Since car seller played with Hybrid battery, and there are 4 errors count on it, It seems that he did more damage to it, I suggest you replace it with a used Hybrid battery. It has some computer stuffs in it and easy to get damaged.