first, no display can be a few different problems. memory and video cards are the main ones.
sometimes there are jumpers used on the motherboard to set up different types of memory use. The manual should have this in it.
If you are trying to use a agp graphics card and get no video at startup it may not be one that is compatible with the motherboard or the mb needs agp drivers installed before you can use the agp port. Mine did and I ended up using a PCI graphics card from a old computer.
from your descirption of the connector, it sounds like it is a on/off button only. sounds like the motherboard is setup for a power button that can be used as a reset switch also. you may have to splice the wires and put different connectors on it. good luck