the hp z2xx series workstations do not use a standard ATX power supply they use a custom supply with a 20 pin connector
instead of the 24 pin one. also the voltages on each pin does not follow the ATX standard
also note that the HD SATA power comes off of the motherboard using a 4 pin to sata cable as i recall
the reasion it will not turn on is because you are applying the wrong voltages to the motherboard pins and causing a direct short to the system. the power supply is detecting the short and engaging the self protection shutdown circuits
connecting the wrong supply can damage both the motherboard and the power supply
you may be able to make or buy a power adapter harness that reroutes the pins to the order the motherboard expects
i would check the HP service manual which lists the pinout and see if the 200/210/240 systems use the same pinouts
then search ebay for a adapter