My Espar D3L will not start. I have run it off and on for 30 yrs.

I recently ran it 12 hours with no problems, then I turned it off, but when I started it up 'no luck'.

When I applied power, it ran for 8 SECONDS then turned off.

I started in "VENT" mode (RED + YELLOW).

What events would make it 'shut down'?