POAOF - engine failed to start

Car is actually a 2009 Camry hybrid but I think it is essentially the same system. I posted this on Toyota Nation forum but after a week there have been no responses so thought I'd give it a shot here. Any tips or advice appreciated TIA.
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Hello, first post here. I apologize for the length but I want to detail just exactly where I'm at with this. I am trying to fix a friends 2009 Camry. It has 210,000 miles on it and it "stalled" on her (her description) She took it to the dealer for diagnostics and they told her she needed a new aux battery and hybrid battery and it would be $4700. So I volunteered to take a look at it for her, I'm fairly skilled as a mechanic but know absolutely nothing about Toyotas and even less about hybrids.

So, first off - the diagnostic report from the dealer says the car had the following DTC's. POAOD and POAOF. I bought a cable and what I assume is a hacked version of Techstream on Amazon and I was able to get it running on an old laptop that still had Win 7 on it. I found the aux battery was low so put a charger on it overnight. I also did a search of POAOD where I saw a YouTube video of how to put the service plug back in. I figured no way it could be that but checked anyway and sure enough it was plugged in but when I pushed down on the handle it clicked. After that the engine started but was running rough and it seemed the battery was charging fine. The "Check Hybrid System" message was gone and using a regular OBD2 scanner I was able to clear a DTC for engine misfire and extinguish the CEL. So I took it for a test drive but after a couple of blocks it didn't seem right and the "Check Hybrid System" message reappeared. I was able to get it back home with only one bar left on the hybrid battery display.

When I hooked up Techstream I had only one code - POAOF, engine failed to start. So more research and today I removed the throttle body and cleaned it and also replaced the spark plugs. Engine still runs rough and idle maybe seems low. Hybrid battery is charging. I might add that in Techstream all of the hybrid battery voltages and internal resistance values are equal - I don't see any dead cells or anything like that. I haven't tried another test drive yet.

So what else can I do? The car is in great shape otherwise, there must be a way to save it from the scrap heap.

Thanks in advance for any help, tips or advice

Paul