Can a P0A80 code be stored for any other reason?

I've done some searching but found no story very close to mine so far so I'm posting.

The non-profit organization I work for owns a 2006 Prius. Back in December it would not start so we had the 12v battery replaced. It worked fine for more than 2 months, then I came out to find it bricked again. I jump-started it and drove it to one of the recycling centers we manage. It operated normally on the way there but then would not start again when I was ready to leave. On another day, I jump-started it again to take it to a repair shop. On the way, the Master Warning, Brake System Warning, Vehicle Stability Control System Warning, and Malfunction Indicator Lamp (Check Engine) lights came on and I lost power going up a hill. I pulled over, turned it off, and it would not start so I jumped it a third time. I took it to the repair shop the next day and they said they tested the 12v battery, said it was defective and replaced it under warranty. On the way home, the same lights came back on so took it back. The only code stored was P0A80, which they said indicates the hybrid battery pack needs to be replaced.

A failing battery pack doesn't seem to me to explain the problems the car was experiencing at first. Could it be triggered for any other reason or does it really need a battery pack?

 

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Oh, I forgot to note that the Hybrid System Warning Light is also showing on the Multi-information display.

Do you think there would be any harm in driving it gently to have it serviced?

 

Thank you. Just out of curiosity I decided to find out what would happen if I disconnected the negative cable on the 12v battery for ~5 minutes. After I reconnected and pressed the power button, the Master Warning and Hybrid System Warning lights are off but the Slip Indicator and ABS lights are now newly on in addition to the Brake System Warning, VSC and Malfunction Indicator lights. Is it me or is this bizarre?

 

I'm not suggesting that nothing could be wrong, but my wife & I have a 2004 Prius with 230000+ miles and all original hybrid parts except the inverter pump. The most expensive thing we've had to replace on it is the Multi-information display.

 

Strike my post above. I thought I had the car in Ready mode but I did not. When I pressed power again, all warning lights went off, so I decided to take it out for a drive. It worked perfectly fine, even on the highway at 55 MPH...for about 10 miles. Then the warning lights came back on and the battery-cooling fan came on loud. Could the problem be that the fan needs to be cleaned?

 

I can understand how driving a car very little causes problems over time but 10,000 miles a year, while less than the US average of 13,476, isn't all that low.

 

I wasn't expecting disconnecting the battery to solve a real problem but was hoping this might still just come down to a glitch triggered by the defective 12v battery's failure. Looks like we won't be that lucky.

Based on other threads I read, I looked at the inverter coolant reservoir and the coolant was not turbulent.

 

The 12v battery was just replaced under warranty as noted in my original post.

I do know a lot of people with Priuses and a few have experienced battery pack failures with less than 150,000 miles on them.