Have you followed the steps in pinwiki? It will keep you from shotgunning.

Basically, disconnect all boards but rectifier board, get those voltages right first.

test your AC voltages from your transformer

I would check your solenoid driver board, after you rule out the rectifier board and transformer. The display HV is generated/adjusted there, and the 5v has to go through it to get to the MPU

Move onto the next board.... solenoid driver. (Nothing else connected just rectifier board and solenoid driver.)

Have you done anything with the connectors yet? (Repin, update solenoid driver board connector)

If you do find your HV section is bad on the SDB, rebuild it all at once if you do one component at a time it could blow the new components as you put them in.

The steps are generic assuming Billc479 means what I think he does.... start with rectifier/transformer. Get everything solid there (which you said you did with the new board right? Got all the right voltages going?). Then hook up the solenoid driver board, do that. Then the mpu board. Then the lamp board. Then the aux lamp board. Then the sound board last. Then the displays.

The original -54 boards are labeled on the bridges with "AC" on the board so you can test between those 2. The other AC points you will have to look at the schematic and traces to test. There's going to be a learning curve on this, I don't believe that pinwiki lists a step by step test here, test here, etc. for the -18 rectifier board either (if it does apologizes in advance). Time to learn how to match what's on the schematic to what you're doing with the meter in real life. Maybe take some pics along the way and when it's correct, update pinwiki (or here, for that matter.)

Rule of thumb for putting your meter in AC or DC - if it's input to bridges, (note that 4 discrete diodes are also a bridge, just without a case) it's AC. If it's output from bridges, it's DC.

telling you PIA is bad. (or if the first flash is the flicker which it is sometimes depending on the board) then the 5101/nvram is bad

flicker=board booted
1st=rom checksum test pass
2nd=6810 ram test pass
3rd=5101 ram test pass
4th=u10 pia test pass
5th=u11 pia test pass
6th=display interrupt pass
7th=zero crossing interrupt pass

luckily Alltek has a lifetime warranty.