01 Prius ICE Starts, Runs a few seconds an stops

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ICE Runs a few seconds, stops an Main battery light flashes. I did get it to run for a few minutes a few times an the power flow screen showed power flowing from ICE to the HV Battey but as it ran the HV Bat was going down in charge rather than up. It was like the older cars would do if you put the battery in reverse polarity, it would show discharge on the ampmeter and would charge the battery down and not up as it should. I'm not sure if it would be posible to have a reverse polarity on the HV battery or how it would or could happen? Another Symptom is that when it Stutters an stops an all the Main battery lights come on the Fan cooling motor also comes on until it turn off ignition. I get a DLC of P1310 The following substitutions have been made with all known good parts: 1- Complete HV Battery along with the relays etc inside the HV battery case, changed out 4 times with known good unit. All work fine in a second 01 Prius I have. 2- Substituted the Inverter/Converter with known good unit. 3- Substituted the Engine ECM with known good. Set up handshake between Transponder ECU an Engine ECM 4-All these Parts taken off the problem car works great on the second Prius. 5- Although I have not substituted the 12 Volt battery, I have charged it an load tested it and it is good. 6-I have substuted the throntle body along with controls etc. with no change. 7- Fuel pump pressure is 50 PSI an Holds 30 #s for over 30 minutes after turning off. I think I need some help here, I'm just about up against the wall. Suppose it could be the radiator cap or maybe I'm holding my mouth wrong when I turn the key? Maybe there is a ghost in the machine??? Can someone please help steer me in the right direction or maybe an idea what to try next???? I feel that I may be an old man by the time I get this thing beat. I guess I sort of forgot, I'm all ready an old man. 72 is not exactly a young buck anymore. I will appreciate any help I may get and thank you ahead of time for any ideas you can give me.