MD3/Ultimax II won't boot, Help!

[gthlm]

Our MD3 stays on 24/7, e-stopped when it's not being used. I walked up to it this morning to set up a job and found the flashing cursor jumping around the corner of the screen. I tried to wake the control and found none of the keys working.

So I tried the next universal step in the troubleshooting process and turned it off at the mains and back on again. Greeted with the flashing cursor jumping around badly in the corner of the screen.

Now, I have a spare set of boards for the machine, including the crt board in the console. I've swapped ALL of them and have seen no difference. I've checked continuity in the ribbon cable between the CPU and crt board. I've spent the entire day messing with it and I'm none better off! Unfortunately I can't be absolutely certain that the spare boards are good to begin with...

Yesterday the machine was running with no issues and the image on the screen was stable.

Of course, there is an important job waiting. If anyone can help me with this I'd be very very grateful!

Thanks in advance, Gregor