If it is a quick "flicker", then I suggest you reseat U2 and U6. Give it a try, then reseat U9 CPU (if socketed).
Try removing all the MPU connectors except J4
report back !
Am I thinking by the above, after reseating and no luck, disconnect the MPU connectors except j4 and then power up and see if the 7 flashes occur?
Cheers Angelo
