Well, the reset signal starts on the power supply board....then it travels through a chip or two on the daughterboard.....then off to the motherboard. Judging by your voltage readings...it sounds like the signal is being generated at the power supply board. You can have issues on the daughterboard....or the motherboard. The signal has to travel through that big 72-pin interconnect. Have you taken the motherboard/daughterboard apart and re-plugged them back together? Also, I'd make sure the signal is actually getting to the daughterboard. Crappy connectors, or cold solder joints at any of the connectors headers could prevent it from getting to it's destination.
Edward