HP Jetdirect 250M User Manual page 271

Resetting the HP Jetdirect 200m
or 250m print server to factory
defaults (cold reset)
Once you configure the HP print server, the configuration settings are
retained in memory unless you manually reset them to factory defaults.
To reset the print server configuration to factory defaults, follow these
steps:
1. Make sure that the printer's power is on.
2. Unplug the print server from the printer.
3. While holding down the Test button on the print server, plug the
print server back into the printer; continue to hold down the Test
button for about five seconds. Any user-configured settings will
be erased.