ok so what i'm to understand is this is a reman/rebuilt controller from FSIP? Not an OEM replacement from NACCO? correct?

ok... LTRM does have a point
i'm sure the guy has checked the main fuse and its not blown?

if all the above is good maybe they should try and get gesentry and a cable and try to access the unit using a laptop when powered on and see if they can even communicate with it.. that should tell the story. I do know for a fact that FSIP does not restore manufacturer specific settings in these and it is possible that the settings may be set to GE defaults, so there could be a setting incorrect. But then again it should code out when powered on. The fact that it is kicking the line contactor out when it tries to turn the system on fully initialized still makes me wonder if there is a hardware/hardwired fault.

If access cannot be achieved via laptop then the rebuilt controller is probably no good. Before anyone says anything about Yale software access through the dash, i am aware of this but you can still access it directly through the port on the controller if you have the right cable using gesentry.
At least to my last recollection this could be done unless they have made some drastic changes in thier dash access system and changed this method of communication through the onboard logics. But the SX controller hasn't changed much on GE's part as far as i know so it should work.