Network Router User Manual

132 Upgrading Your Modem
10. When the installation is complete, the modem restarts
automatically.
Kernel Recovery Mode
Your modem is equipped with ZyXEL’s exclusive Kernel
Recovery Mode. This unique feature enables quick recovery from
failed flash uploads. With other modems, a failed flash upload
usually results in the user having to return the modem to the factory
for repair.
In the unlikely event that your modem fails to respond to AT
commands after upgrading the flash EPROM:
1. Turn off the modem.
2. Press and hold down the A/O button while turning on the
modem, then release the button after 5 seconds.
3. A Kernel Program responsible for the update process takes
control of the modem. It accepts a limited set of AT commands,
including the ATUPX command.
Repeat steps 1 through 6 from the directions above to upload a file
that contains valid firmware for your modem.