Rottendog do make some very good boards , but the power supply's for Williams and Data East games arn't one of them.
The reason they are inexpensive is because they are made cheap.
I had a Lethal Weapon to repair not long ago with display problems , lighting up too many pixels.
The owner had bought a brand new Rottendog power supply for it recently along with a cpu board.
The voltages coming out of the power supply were wrong and where it should have been giving out +100 volts it was giving out +140 volts!!!
I sold them a good rebuilt original power supply and all is well now.
Extremely lucky no damage was done to the display , i got them to send the board back and get their money back.
I also read of a couple of other people having problems with them on RPG

Get a new multimeter and check the voltages from the power supply with no other boards connected to make sure they are right.
Sounds like you've done a bit of damage to your boards.