Frage SC600 died mid-run

I need help guys. My 600 died mid-run. The HF spindle and all axis movement just stopped dead while running a cutout program. I did nothing to cause it as I was just watching it at the time.
I checked the following: all plugs were in the wall sockets correctly (i.e. not loose), the lights on the UC100 were both on. The spindle controller was on and the speed indicator showed 0 (as expected since the spindle had actually stopped).
When I checked the diagnostics screen on UCCNC, all lights were out, and I mean ALL. No x, y, z or probe lights come on - not a single green light anywhere. There is now no reaction from the machine when I try to manually move the spindle up, down or sideways via UCCNC.
I tried rebooting UCCNC and restarting the 600. It was then that I noticed that when switching on the machine there would normally be a faint whirring noise , like a small fan starting up - there is no buzzing now - like the fan (if that is what it was) has also stopped. The machine is completely dead in the water.
I'm no electrician or electronics guru. I know nothing about circuit boards but is it possible the board has just decided to die? I lifted the machine up on its side and removed the bottom plate but all connections seem fine.
Regards
Craig