Fruit Machine Chat

hi, any help would be greatly appreciated with my friends barcrest "phil the power taylor" £35 machine.
he came down one morning to find that the machine when switch one wont boot up. when you lift the door, there are lights on the mpu 5 board. there is a bank of green ones and next to them, there is a green one that alternates between red and green slowly. the one next to that is red ( says this is the halt one). we have tried pushing the reset red button on the board to no joy. we removed the cartridge from the mpu5 but everything seems fine. we then disconnected the coloured ribbion cables around the mpu 5 and removed it. we took the cover off and again everything seems fine. the battery is the coin upright type but theres no sign of leaking or damage. I have read that most of the issues with mpu 5 boards are battery related, and this battery is not the rechargeable type. does anyone know if replacing the battery would help? would a dead battery indeed stop the machine from booting up? or from my description does the problem lie elsewhere? its a great machine in first class order, hopefully its a simple fix. sorry about putting bellfruit in the header
any help really appreciated.
davy 22

the led that flashes both red and green is the status led.

it is trying to give u an error cpde.

count the flashes.

example:
2 green 3 red
4 green 1 red

should give us some idea of what is going on