I would normally blame power for that kind of behavior, but if you have already swapped power (I assume the spare power supply is good) and have the same results, the next thing to try would be the controller. Power up the dot display by itself (disconnect all other connections to cabinet other than power) and see if it power all the way. If it does, then there's something with your cabinet that is causing it.
To change from canadian to US, you just need to change the validator to a US validator. What validator is in it now?