HV Battery Pack Replacement for 2005 Prius

everyone! First-time poster.

The car: A 2005 Gen II with about 130,000 miles. I love my car and it's been very good to me up until this point, and I'd be happy to keep it going until 200k/a few more years. There's been nothing but two 12V battery replacements and some Toyota recalls since I bought it in 2007-8.

The tale of woe: In April, I was rear-ended. I went to the body shop recommended by my insurance and had a new bumper installed. As I was leaving, a mechanic (different from the one who worked on my car) stopped me and told me that my taillight was out. He said that they couldn't repair LED lights, it almost certainly had nothing to do with the accident, and I should just get it repaired. I know the LED light was working prior to the accident but didn't think to check my lights specifically afterward, and the mechanic only looked at the external damage when I brought it for an estimate.

That was on a Saturday. The next weekend, on Sunday, my 12V died. I got a jump from AAA and had it replaced at an Autozone. I also had an appointment made to get the taillight replaced. In the time between having a new 12V installed and getting the car to the new auto repair place (a Toyota specialist), the check engine light and red triangle went on in my car (when I needed to pass a smog test yesterday). That place ordered the wrong part, so I needed to make another appointment to get the part I'd already paid for installed and to diagnosis the check engine light. I do that today, and I hear back that I need a new HV battery for $4k+ (also, brake service for $500, but one problem at a time). I called my insurance, and they said that I'd need to take it back to the body shop to determine if any of this is related to the accident (and pay for it if it isn't).

I've had a rough few months with lay offs and medical bills and a car accident and have just gotten a new job, for which I need a car. I flat-out don't have the money for a new battery pack at the moment, much less to purchase a new vehicle. So my questions are threefold 1) Is there any chance this is related to the accident and if so would there be any way a mechanic could tell with the 12V battery already replaced? I don't want to take it back to a body shop I wasn't happy with just to have my insurance nah-nah at me. I'm also not sure a body shop is equipped for HV issues with a Prius when they weren't equipped to repair a taillight. 2) Is a service like Hybrid Battery Repair in North Hollywood worth it, especially as I have limited options and need to get my vehicle re-registered STAT? Does anyone have personal experience with them or their batteries? 3) Does it seem even a little possible that Toyota would help me out? Would it be worth it to approach Toyota/local dealerships and see if they'd do a payment plan on the battery, if not knock off some cost? I have gone to them for maintenance in the past, albeit mostly in a different state. I do not feel equipped to do anything with the battery myself.

I will greatly appreciate any guidance.