Unbricking
If your Fonera stops responding after an update, fear not! It can be recovered.
These directions were taken from http://www.mcgrewsecurity.com/blog/?cat=1.
Redboot listens on port 9000 of 192.168.1.254 for about ten seconds upon boot before it moves on. You have ten seconds to send Ctrl-C on this port to stop it and allow you to interact with RedBoot.
It’s easiest to just use this script, redboot.pl, to connect to RedBoot. Leave it running on the computer you’re configuring this from, plug in the router, and it’ll connect up for you and leave you at a RedBoot prompt.
1. Give your computer an IP address on the same subnet $ sudo ifconfig eth0 192.168.1.2
2. Press and hold the reset button for 15 seconds, then unplug it and plug it back in. I don't know if this is all really needed, but it worked for me.
3. Connect the ethernet cable
4. Run the redboot.pl script: $ ./redboot.pl 192.168.1.254
5. You should now have a redboot prompt, and can reset the flash and install new firmware. RedBoot>
Resetting
Recovering from a lost root password in dd-wrt (and presumably unknown network configuration)
appears possible by pushing the reset button on the bottom for a couple seconds and waiting for a reboot. You can then reconnect to 192.168.1.1 on the ethernet interface and login as root/admin.