2010 Prius Temp light flashing. Car shuts off.

Red temp light on dash flashing. Changed water pump and thermostat and still overheating. After 10 minutes or so engine shuts off after going into what I think is called limp mode. Then the red triangle and Check Hybrid System light is on. Sounds like the problem that Toyota denies is happening and refuses to acknowledge. Any ideas on how to fix would be appreciated. Toyota obviously does not care.