To reset the printer (does not reset the Jetdirect network card), turn off the printer. Upon turning it back on, immediate press and hold the green go button for at least 10 seconds but no more than 20. During that time, the attention light will go on. When that happens, release the button and the printer will cold reset.
Resetting the network card is done a little differently. With the printer in the ready state, press and hold the rotate carousel button and the cancel job button at the same time for a few seconds, then release it. This will reset the card to factory defaults (BOOTP/DHCP, no management password). If a network cable was inserted, you'll notice the LED at the NIC port go out for a few seconds, indicating it is resetting.