i would be making sure you have 12V dc at TP2, and 5V dc at TP5 on the mpu board, if these voltages aren't right then you wont be getting any mpu to boot.
you need to check if you get a flicker then it locks on or if it just locks on straight away,
1st flicker indicates the cpu has booted and found the startup code in the rom at U6.
on rare occasions a faulty PIA at U11 can also make the led lock on,
it could just be a faulty cpu chip or faulty roms.
your mpu board looks pretty clean
But long term i would go the new homepin mpu board, they are so close to the original board except some things have been improved and obsolete I.C.s have been replaced with readily available I.C.s
They are repairable if they ever fail or are damaged and you don't have to worry about custom programmed chips failing and the board becoming a paper weight
the display fuse blowing is a separate issue as mentioned.
