Synapse 7.2+ High Mains Power Consumption When idle

Good day All.

I have a synapse 7.2 Kva inverter for repair that came in with almost all the HY3215 physically blown apart (the 12 fets connected to the 48v rail)

It appears the battery was connected with reverse polarity.

After replacing these, several smd resistors and a faulty control card (sourced from a scrapped inverter) there was a F09 error after replacing the 12 FETs,the inverter seems to work as it should including charging the battery from AC mains and PV.

The 3 low voltage secondary smoothing caps that commonly fail have also been replaced (for the pos and neg 12v supply)

The issue I cannot resolve is that even with the AC grid charging disabled and no load connected,the inverter consumes over 10 amps from the AC mains supply.

When connecting mains power the inverter consumes the normal 2 or 3 amps for a short time then suddenly jumps to over 10 amps,I do not smell any burning or feel any component or heatsink unusually hot.

I have checked all the FETs and IGBTs as well as the bipolar capacitors around the buck regulator and full bridge transistors.

The bus voltage does not decay quickly after powering down so I do not believe there is a low resistance fault here that may be causing this excessive power consumption.

Has anyone had such an issue before and can help to resolve this ?

Cheers