If you want to repair your configuration, you first need to mount the root filesystem. This is best done via:
# mount_root
After that you need to enable the FreeWRT configuration filesystem:
# fwcf setup
Now you can change files in /etc/ and repair your broken configuration. Do not forget to commit your changes afterwards.
# fwcf commit
If you want to start over with the default /etc/ directory, just remove the fwcf partition content with following command:
mtd erase fwcf
You can either use reboot -f or the option -r for mtd to reboot the system.