Hybrid inverter / converter internal failure

My 2005 Prius (165,000 miles) got the red triangle of death. Took it to a dealer and they said its error code P0AA6 (hybrid battery voltage fault system isolation fault) due to an internal failure of the inverter / converter assembly, part number G9200-47100. They want $5600 to repair it. The part itself is nearly $4800 from Toyota. They did not provide any subcodes (and I didn't know to ask until I started doing some research online). I found new aftermarket parts for $3100, salvage parts running about $200.

The dealership didn't say anything about the cooling system or needing a replacement pump. I doubt his vehicle received a new pump during the extended service campaign that ended in 2013 because I didn't own the car then, but my sister did and she doesn't remember any extended service campaigns, just 1 recall. So I haven't even looked at pump replacement, though that seems like a very common failure.

The car turns "on" via the auxiliary battery in the sense that the dash lights up and I can put it into Neutral (thankfully) to roll it onto a tow truck. Car was just towed back to my house yesterday because it'd been sitting at the dealership for over a week.

Has anyone replaced this part before? What was your experience? I'm debating spending $200 on a salvage part vs. spending the money on a tow truck to take it to the junk yard. I've found a few youtube videos showing how to replace the part, but there seems to be some internet discrepancy about whether the replacement inverter / converter needs to be "programmed" or "calibrated" to the other electronic systems in the vehicle.

For reference, in the last 2 years, I've replaced the hybrid battery itself (Dorman, still under warranty, $1300), the auxiliary battery TWICE (upwards of $700 total), and the front dash computer component when the entire dash went dark ($900). I'm willing to spend a few hundred dollars, but not $3000 on a car that's 13 years old with a horrible record as soon as the 10 yr/150,000 mile warranty ran out. I'd rather take that $3000 as a down payment on a more reliable vehicle because I've lost all faith in the Prius model.

Please let me know your experience or suggestions. I won't be doing the repairs myself, that'll be my husband's task and he's very mechanically inclined and fully capable, buts he's currently out of state on military base so I'm gathering suggestions until he comes back and decides which direction is worth the time, money and effort.