Prius gen2 weird issue - enginer jerking while driving, ICE won't start

I would like to give a brief timeline, although the issues might be all separate and unrelated.
Also note the battery did not show any sudden SOC changes. I get around 43mph. The car has 143k mi on it.

May3rd - Bumped a car while reversing, got minor, scratches on the left rear on the bumper
May 15th - In morning while raining ABS/Brake lights came on, brake were on manual but car was driving ok. Went to a local mechanic he said most likely rain it should go away on its on. In afternoon when the rain stopped and it did not go away I reset the ABS system by shorting pin 4 and pin13 in the 20 pin port above the right knee (I think I had to pump the brake 8 times in 5secs in the diagnostic mode). Problem went away and car started working again.
May 16th - Car was fine to and back from work, but now thinking about it, I did seem to think the car was revving a bit higher and may be a bit more responsive.
May 17th - On drive back from work. 30mi into the drive had the traffic really slow down, and I noticed at low speeds the car was sputtering and jerking quite bad (around 25mph) after a while got the flashing lights on the dash and realized the car was just running on limp mode). Pulled over restarted the car and the engine started working again normal.
May 18th - Took the car to the mechanic, he pulled a p3191 code. He changed air filter and cleaned the MAF sensor.
May 19th-20th - The car worked fine.
May 21st - The issue came back while on the highway car starts, sputtering and jerking and loosing power, I kept nursing it. I noticed the jerks were synced to when I would see the ICE transitioning. Also noticed if I had room to accelerate fast then the ICE would kick in fine and there would be no jerk. As soon as I would let go I would get the jerks. I got home and parked. Restarted the car but could not get the ICE to start (it was in the driveway so had to reverse out, seemed worse in reverse). Oh right at the time when I would expect ICE to start, I sense a slight wobble as if a very weak attempt was made to start it.
May22nd - The hybrid battery by this time was almost drained so had it towed to the mechanic. Later the mechanic called back saying he pulled p0A80. So he said your hybrid battery needs changing, and even after that he says one of the motors (he said the big motor) might need replacement. So basically at this point it might be not worth to spend any more money on this car.

Somehow I am still thinking its just the ICE not starting that is the issue, and that the hybrid battery while old might have given a random P0A80. My question is whether the community here has any tips or ideas or whether anyone has had any similar issues? At this point I want to make sure that what my mechanic is concluding is correct and that may be it is time I just get rid of the car, which I like quite a bit. Thanks!

 

Thanks for the quick response. I think I got the spark plugs changed last year. I have asked the mechanic to check the 12V battery. The car has 143K mileson it.

 

So on the display it still showed one red bar, from what I have read 0 bar corresponds to around 40% charge on hv battery.

I read on another thread that someone had ICE not starting issue, and for them the issue was a fuel line 0-ring. Whats an o-ring and could it cause the symptoms I mentioned above?

 

Update: My plan was to tow the car over to a Toyota dealership tomorrow for a deeper diagnostic and a second opinion and thinking that the car might be inoperable or a few days I wanted to take out my son's car seat, so I went over to the mechanic's and got the seat out. And just for the heck of it I started the car and the ICE just started like normal and started charging the battery. Once it was in the blue I drove it for ten mins and the battery got charged up to around 60%. I will still tow it to the dealership and have them do a diagnostic.
Now I am thinking unless the dealership comes out with a better explanation I will try to put in some fuel cleaner and just try to see if the problem just goes away.
I double checked with the mechanic earlier today and he said the only code was a P0A80.
One question I have is whether this code occurs intermittently.. or in other words whether the battery behaves abnormaly intermittently before giving up altogether.

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No he just checked the battery and said it was ok.

Update: Yesterday after work, I drove the car to Watertown toyota for a diagnosis, and the engine was working and the battery was charging. And now the dealership just called me back and said that the engine is blown and that the battery pack needs to be changed. For the engine they said they have a replacement engine with 94k miles with 1 year warranty for 3.3k$ (including labor). I asked for all the codes for the engine and they said there was no code. I don't understand how the engine could be blown and then work on some days (engine did not start for them). The person on the phone said that the guy who worked on the car is a master technician and he knows what he is talking about. I told him the engine works on some days and its intermittent so he is going to talk to the tech again.
After having towed this car around and losing a couple of work days I am kind of not sure how to proceed further. I had almost made up my mind after reviewing the excellent resources available on this forum to try rebuild the battery pack over the long weekend, but not so sure now.

 

Thank you for your reply, it helps already, gives me some place to start. So far unfortunately I have had restricted access to the car since I have just been towing/driving it around after work while figuring out how to pick up my son from daycare etc. I am going to try some debugs myself over the long weekend.
"prolong charger setup": You mean if I take out the HV battery pack I could balance SOC?

 

I don't have the car in front of me, so I could not check as yet. Can you specify as to the location of the bolt, or is it just easy to trace by tracking the 12V battery ground terminal?

 

So brake and abs lights were on, and the brakes where very hard to press but were working..

Thanks for the battery link, I was just looking it up actually to be actually to check that tonight!

 

Also just a small update, I drove the car back, it drove ok the engine sounds much louder.. kind of like in this video here:

(The dealer told me to replace engine)

I disconnected the battery for 10m and hooked it back up and right now car is driving ok, but these days i am using my friends beater car. I am thinking of getting a mini vcl and prolong harness.

 

Is it ok to just buy this mini VCI here:
amazon link
And I am wondering if there is a version where I can connect it to a cellphone?