New NF7s system won't power on

Built a new NF7s system tonight, and it won't power on. Hit the power
switch, and everything comes on for about a second, and then back off
again. I have to turn it off at the power supply long enough for that
little light by the power switch connectors to go off. Then, when I
turn everything on , it will get power for about a second again. I've
tried a different power supply, different RAM (in every slot),
different CPU, swapped the reset switch to the power switch position,
reset the CMOS jumper, and tried it with every different power plug
plugged in, and removed.

Any ideas?