Hi,
if one or more of the IGBTs have failed (shorted) then at turn on the inrush current will blow the input rectifier and/or the precharge circuit.
If I were repairing it ( I fix welders, inverter welders particualrly for a living) I would try to disconnect the DClink voltage from the IGBTs to see wether the input
rectifier, precharge and link capacitors are ok. Would also tell you wether the flyback inverter is still running. The flyback inverter is responsible for all the DC
auxilary voltage including the fan.
Craig