Dudes, today i installed a cr2032 battery, but i am still missing something...
I had to install the battery without holder (i made the soldering directly, but firmly, on the battery) (notice that the pcb is upside-down and only the black cable coming from the positive hole and going to the battery is connected)

Even if the 3 V are supplied, nothing changes: if i restart the machine, i have the bookeeping reset and the game doesn't start.
In addition surfing the "advance" menu, i have this:

... maybe some wiring is missing? I have not connected the switching on the front door and the back door, so the message sounds odd to me...
thanks for the help

EDIT: my wiring was missing the "memory protect interlock" connection from the CPU board to the coin door: when the coin door is open, that switch is open, when the coin door is closed, the memory protect connection is grounded...
The game shows the high score table for a second, then restart... i have checked the voltage supplied and it's ok (5V).