I just had the same issue. The led matrices burned out. I ordered a new set and they burned out again within a week. The voltage regulator goes bad on those boards. You can tweak and adjust it, but it is simpler just to replace with a dixmor unit. Get the one with the brackets if you order from
kleen rite snd they mount in the same box as the old board (they are half the height as the old board as well)
In one of my units the replacement was straight forward. The other one i had to add a wire from the selector to make it work right.
Programming them is a bit of a chore, but now they are solid and working flawlessly.