HELP! red triangle/check engine/VSC lights on. Not inverter coolant/pump! Techstream data included!

I have a 2005 Prius with 204k miles on it that recently lit up its red exclamation triangle warning light, its check engine light, and its VSC notification after a routine stop for gas. All lights have remained solid since they first lit up. I have downloaded Techstream data using a mini-VCI cable, and have tried to track the usual culprits before posting here; Techstream screenshots to follow.

Old hands here may recall the 12V auxiliary battery problems I had and that the group resolved last summer, when the car had 193k miles on it: Prius with 193K miles and repeatedly dying 12V: repair or donate? | PriusChat

History: The car was previously being driven upwards of 80 miles a day in Northern California. We've moved to coastal Southern California and the car is being driven much, much less now, sitting unused for days and driving only a few miles a time in the relatively compact confines of coastal SoCal. I suspect we might have a problem relating to charging up the main battery sufficiently, but that is just a guess. We could start driving the car much more regularly (probably 40 or 50 miles, every other day) if that would be helpful. Or, the car may be headed for the great scrapyard in the sky. I would appreciate your counsel.

Ruling common problems out:
* I checked the tightness of the gas cap. The cap is tight. The warning lights are still on.
* A common cause of these problems is the failure of the inverter coolant pump. I checked that it is functioning, both by feeling vibration in the coolant hose and by visually inspecting the surface of the inverter coolant, which exhibited rippling from the operation of the pump. The level of the coolant is normal.
* The 12V aux batteries rest voltage appears to be normal, and the car isn't exhbiting the usual failure symptoms of dying 12V batteries.
* The car is full of gas.

The car starts and drives "just fine" despite the presence of the warning lights, but I haven't driven it more than ten miles or so since noting them out of an abundance of caution.

Techstream (which -- caveat -- I used for the first time tonight) reports at least the following error codes when the car was freshly started after hours of non-use, as I sat in a parking lot:
P0A80 Replace Hybrid Battery Pack
C1241 Low Battery Positive Voltage or Abnormally High Battery Positive Voltage
C1300 ABS ECU Malfunction
C1378 Capacitor Communication Malfunction
U0293 Lost Communication with Hybrid Vehicle Control System.
C2318 Low Voltage Error (Power Supply Malfunction)

Any ideas or suggestions on this one? I'll follow this text with screencaps of the various Techstream diagnostic screens, including detailed voltage data.

Thanks in advance! I would like to keep this car running another year or two if I can.

 

What will happen if I keep driving the car as it is now? Is there any chance this problem will clear if we start putting regular mileage on it again?

I would be willing to spend the time to rebuild, and I have the tools to do it. I watched the video on how to extract the battery from the car. But I am concerned about getting killed in the process of fixing it by high voltages. Are there any quality videos that accurately explain how to eliminate the electricity risks?

Alternatively, if people have suggestions for a rebuild/replacement service in SoCal, I might be interested. The car seems to be running well otherwise.