Changed battery, water pump, inverter & ecu still not working, what is wrong?

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I have a Prius 2007 that is not working right now. After changing the battery twice, the water pump, the inverter and the ecu. And the car is still not working. My mechanic which works for Toyota doesn't know what else to do and we already have spent too much money on this car. What else could be?, the computer to troubleshoot doesn't show any more signs, it's says that everything is fine. But the car keeps on getting some weirds lights on and not working.