DC-DC converter failure or am I missing something?

08 GenII
149k
Original traction battery
12v battery ~2 years old

This weekend, I re-started the car after going on a few short drives during which it had performed normally. The red triangle popped up along with a host of other warning lights and a shrill beeping sound. Brakes felt a little less assisted. I power cycled the car cycle times with no change. OBD scan showed code P0A08 - DC/DC Converter Fault Circuit Open. I cleared the code and re-started the car. Drove approx 25 miles with several stops, no issues. The red triangle/shrill beeping re-occured once in an intersection at the end of the drive and stopped after power cycling the car again.

I drove it home and got out my tools. Multimeter shows ~14v at jump starting block & battery terminals at idle. I load tested the 12v battery and it tests very strong especially for a battery of its size.

Hooked up OBD2 scanner and logged data for ~45 minutes of drive cycles. Naturally, the car performed flawlessly while I was data logging.

The next day, after several short drives, the fault reoccurred. This time, I was able to see that the OBD reflected the current voltage as ~10.8v at idle. The terminals of the 12v battery reflected a similar voltage at idle and also with the car powered off. I power cycled the car and it performed normally. After several short drives with the OBD voltage showing as its normal 13.9v, the 12v battery recharged to about 12.7v measured with the car powered off.

- *No* jump starts or any electrical work has been done on the car within 2+ years of ownership (unless replacing headlight bulbs counts, lol)
- No fault codes are in the OBD related to the traction battery; the Dr Prius app shows the traction battery to be in fair condition with about ~60% capacity remaining. (Note: I wasn't able to use the Dr Prius app to test for fault codes and found it to be disappointing in this regard)
- The jump starting connections in the fuse box area under the hood are clean and tight
- The battery terminals on the 12v battery are perfectly clean and tight
- I did check to verify that the inverter cooling pump is operational; it is, and the coolant is full. I don't think these symptoms sound like the inverter is overheating but thought I would check regardless.

These symptoms seem to point to failure of the DC-DC converter within the inverter. This seems to be uncommon. Many people suggest that this is caused by some sort of electrical tampering or by someone jump starting the car backwards, but this car has not been jump started in 2 years. I bought it 2.5~ years ago after it had sat for an extended period of time, replaced the 12v battery and it has driven flawlessly since- I've put about 19,000 miles on it.

Am I missing something, or should my next step be to replace the inverter or at least the DC-DC converter board inside of the inverter? Troubleshooting advice or advice on if I should replace just that board, some part of the inverter, or the whole inverter, is appreciated.