P3004 & U164 - Urgent Help needed

So this 12 prius was at dealer, Was diagnosed and had these 2 codes

P3004 High voltage Power Source
U164 Comm error from A/C ecu to HV ecu.

I replaced the Inverter as they said it was bad. Still the same 2 codes come up. Got another inverter same codes

Fuses are good.

Now when IG is on. The radiator fan goes high speed. Typically when this has happened on other cars it was a bad ECU or a plug not fully plugged in.


Car was driving fine. Went to part it overnight then it would not start in AM. Shows check hybrid system and check pcs system.

Any help would be appricated!