10.2 is a little low.
check what voltage you have at the capacitor marked "for BR3 display" you should have around 12V
check what voltage you have at J4 red on pin 3, black on pin5 (Where there are no pins just solder pads) on you dmd driver board, you shouls have 5V. if you do have 5V This test will prove that the 5 volt connection at J1 is good an the dmd driver board is getting voltage to it.

Since you have had the machine have you ever had the dmd working properly?
If not then there may be a problem with the dmd or the dmd driver board.
If the machine boots and runs in attract mode, you have replaced the ribbon cables and ensured they are fitted correctly plus you have 12v at the dmd and 5 volts at the dmd driver board then you will need to test the dmd driver and dmd in another machine to work out which part has the fault