I have the same problem with you. My car has low mileage, 70K and Toyota dealer said "what do you expect? This is a 8 year old car."
I didn't know Toyota cars are common to have a $10,000 bill to fix it, if it is 8 year old.
Anyway, I found that Toyota America recalled the inverter because of a manufacturing mistake.
So, I requested them to provide me the details of the inverter manufacturer, but Toyota and the dealer refused to do that playing ping pong each other.
I guess their water pump has a failure and it overheats the inverter or a strong sunlight might do it.
I wonder how did it go for you.
