Bad HV Battery, Recently Replaced 12V, Now, not even starting...

I have a recently purchased 2005 Prius- Mileage-150.3k having several lights on the dash: ABS/VSC/Engine Check/ Brakes, etc. See attached screen shot. Initially, I got into the shop and had the codes read out several codes. In all, I was informed the root cause was a bad 12v and bad hybrid batteries. By this time , the car was still moving, though not very smoothly. however, less than a week thereafter, the car couldn't start again.

We decided to replace the 12v first, hoping to get it back to start but it wouldn't. I've checked the fuses in the engine compartment as well as on the steering column- all okay. I've checked battery voltage, it's now at 12.3v. When I try to start, the Ready light would simply flash for 2-3 seconds before going off. I've rechecked battery connections as well as the brake controls by the 12v battery- all well tightened.

My question now is: would the bad HV stop it from getting into a Ready state? Are there other issues that could be wrong with it? How do I go about this? What else do I check?

 

I think it was about 12.6 or higher but as I continually tried my hands on different checks/start attempts, it gradually went really down and I had to connect another battery to it-using the jump starting procedure. This charged it up to that 12.3. I guess I'll have to boost up the voltage again to a higher value then. On the battery negative lead connection and bolt to the body of the car, yea, I checked that, its quite tight.

 

After replacing the 12V, the following are the codes I pulled using my Innova 3100f OBD 2 scanner: P0A80 (Replace Hybrid Battery), P3000 (Battery controller , I guess, not too sure) and B2799 (??) . Perhaps more codes could be pulled using a shop scanner...

 

Is it possible to completely drain the HV yet still have one red bar on the battery indicator? (Please see attached screen shot on post #1)
(However, they are times that red bar wont show and 'twill all be plain without any battery indicator bar shown-although this would often change back to one bar .)

 

[QUOTE="What state do you live in?"[/QUOTE]

I'm not in the US- in Nigeria although the car was originally owned and used in the US by the previous owner. So, I know my options may then be limited as I cannot call or drive into any of the reputable workshops mentioned here on PC. Nevertheless, required spares (HV, etc) shall however be imported from the US as we do not currently have the hybrid spares readily available even by the toyota shops around here.

 

JC:
Just did that- disconnected for about 15 sec and got it back yet no change. "Ready" light still flashed twice and was gone. Still not starting.

 

Thanks JC but what's an "Immobilizer Problem"?

Plan right now is to identify the issues as well as the most cost effective/dependable solution providers there in the US and make an order accordingly. So, please feel very free to offer recommendations on required spares and checks.

 

[QUOTE="JC91006, post: 2018133,

Your car's security system is not recognizing your key. So it won't let you start the car.[/QUOTE]

How would this be? The smart key is still activating the security system- still locking and unlocking the car as its used to. Would it activate the security system and not be functional in starting the car? I may be wrong, just need a bit more clarification.