It looks like there are credits on the game. I assume you can't start a game? Make sure all of the connectors are seated properly on the MPU. If the connector for the switch matrix isn't on correctly, you won't start a game. Also, make sure the connectors for the MPU to sound board are correct as that can create problems too. If you're not sure, unplug the ribbon cables off the sound board and see if you can start a game.