Restoring Firmware

=Fixing a bad flash= I recovered a used Zyxel unit purchased from amazon using this method after some experimentation.

If your zyxel unit does not boot: Symptoms are booting up - no network connection - and green flashing LED on front that just keeps flashing forever.

Also Try the USB recovery method first. If that does not work - then your unit may have a corrupted NAND.

The best way to detect this is with serial cable. On bootup if it gets stuck on Stage2 after the kernel - with the error in the serial terminal:

If the internal mmcblk partition is corrupted. When this happens the boot will not get past stage two. You can do the following over serial - or using a keyboard - but using a keyboard you may not be able to see if you typed an error.

First download the recovery file and unzip to the root of a fat32 formatted usb key: 450AFO1C1_UpgradeKey.zip from: 

Now either over serial or with a usb keyboard type the following:

If things go well your unit should shutdown - turn it back on - and things should be working!