In some of these monitors, the ribbon cable was slightly smaller then the actual plug. The ribbon cable is the one that connects the buttons with the controller. For example the plug has 14 pins and the cable is 13 pins. If it is not aligned properly then you will not get it to power ON. I believe it should be aligned to the left.
I don't know if this is what your problem is but definitely check it out.
Originally Posted by Glyn