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

Update: I had found a mechanic who was knowledgeable with electronic automotive systems in Revere and someone who had worked on this same car for the previous owner. He diagnosed the car, and he said I should find a regular mechanic who is good, because the CVT fluid was almost gone and no one flagged it, he was surprised that the engine was even working. He also found misfire on spark plug#1. He is still going to drive the car around today to look out for any weird symptoms and to ensure the problem does not come back at least for today. I am keeping my fingers crossed and will drive it for the next few days.

I am just wondering if this explains all the symptoms..
May be the CVT acting weird and causing jerks could cause ABS/Brake. May be the combustion engine not being engaged properly could stress the hybrid battery more (P0A80 not sure). Or may be this is an unrelated issue and a sign that at some points the battery is going to go. I am thinking that if for the next couple of weeks the car drives ok, then I should invest in a battery prolong harness, The only is the $658 price tag. Not sure if there is a cheaper alternative? And I am wondering if this investment is worth it?

 

Update: So I got the car 6 days ago and it had been driving smoother and quieter and now since yesterday the same problem has been coming bad, and the engine noise is back again. Its sort of a whirring noise. The mechanic had found almost no ATF and diagnosed that the axle shaft seal had been leaking and he replaced the seal and refilled the ATF. May be th e leak was somewhere else? I am not that familiar with the transaxle. Is there an easy way to check the ATF level? Otherwise I will drive or tow the car to the mechanic.

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I found this video, so it's not complicated but not easy as it needs a lift. I don't have a tool to torque the plugs properly either

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Also found this earlier thread from where the axle shaft seal replacement had to be redone a few times. I won't be surprised if it's something similar. Need help with Axle seal from a toyota mechanic!!! please? | PriusChat

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Update: So last weekend I had the car towed back to the same mechanic. He checked out and found that the CVT fluid was holding He took out the inverter and found that the engine mount was broken/loose. In the meanwhile he says that the hybrid battery has no charge now and might need replacement. He does not know how this could have happened. I think all of this towing/not driving may have pushed the battery over the edge.
I am willing to spend some money and replacing the current battery with a rebuilt one, but what I am scared of is that even after replacing the HV battery there might be some other issues which has been making the engine stumble/get rough etc. I am not sure how a bad hybrid battery could result in all these symptoms.
My heart says its battery and something minor but my brain says to junk the car and cut my loses.

 

Also I am remembering that a couple of months ago the Sullivan Tire who do my service/mantainence had asked me as to where i park my car, they had said that there were a lot of debris in the air intake filter, which they had changed. I am wondering if its possible that some debris got inside the intake system and are still there, and cause intermittent problems with the engine?