I have experienced a possibly similar problem with my 2003 at 25K miles. IMA and check engine came on (but nothing with the fan) and the car stalled out going down the road, then recovered a little, then died in a driveway, wouldn't restart. After towing it in next morning, dealership says they never saw those lights come on and can find no problem. I took it back once and the hybrid battery gauge was staying at only half to one quarter whereas it usually shows either nearly full charge or recovers quickly. Took it back again and they say they drove it 30 miles total and no problem, I have to take back the car unfixed or as they feel, it doesn't need repair. I live in a place (Hawaii) with dangerous roads, no shoulder, lots of narrow bridges, no place to safely pull over if it dies again, and I no longer trust the car.

Anyone have any suggestions on what could be the problem or had a similar problem?
The only warning prior to the breakdown was some difficulty re-starting it after a quick stop, about 3 days earlier, it was like the battery was dead for several tries, then it started and ran for a few days and 3-4 hours of driving. That first time, no warning lights came on with dash, and it started, so it seemed like a fluke.