Black knight dead

[slither]

So my Black Knight went dead last night. Played for a bit, was all good. I left it on in attract mode for a few hours, went back and all I had was backbox lights. After checking connectors, I got the gi lights back. The Mpu seems to be booting, getting the quick flash of the 2 LEDs and a 0 that both go out immediately. All boards were professionally redone last year. Checked all fuses. I even swapped out a driver board and power supply. There is power to displays as well, small glow in bottom. Not sure what happened here..any ideas?

[ToMMy]

Press the lower of the two pushbuttons on the left side of the MPU board, what error code number comes up on the red single digit display?

[slither]

None..it does not light up, if I press the top one it says 0, and the 2 LEDs light, but bottom I get nothing....