Bally 5500 weird message on display

[Gorgar]

I have a Bally proslot 5500,  "SEVENS" game ,who was modify to be played on New Jersey arcade for
token payout. So the MPU was a "Jobber one", not a original Bally.
Since yesterday, i have the following on digit display when the slot is booting : F F F F F F F F F F
After the boot, i have on on top line: b.b.b.0.
If i put a coin and star the game, the dot between the "b" desapear and the "coin in"
always say "0" but the game like to work properly. Also, the game don t show the payout token amount.

I search for a "reset" switch, but dont look like having one! Is that possible?
(on the main board reset location from tiror, dont get any reset switch inside, the actualy board
is smallest then the original one)
Try to unplug from the wall for many hour, that change nothing. I alson try to pull and re install
the CPU tiror, nothing!

Did someone can help me to get back my properly display use? Thanks