Sometimes pocket money isn’t enought for buy new network devices or we want to save some money changuing no existant money for personal time. In my case I needed to create a wireless bridge in my personal network, pass a ethernet wire between two builds wasn’t an option. Searching in my forgoten stuff boxes i found two foneras model 2100. Fon’s firmware isn’t powerfull enought to get wds and when these things happens Free Software is our solution. 
I’m a lucky man and I also found a usb to 3,3V serial adapter, one of my superpower is that i can brick everything. First of all we need to plug our serial adapter into fonera’s port, check the attached image for see jtag pinouts 
when we have our jtag port connected we need a software for send data over jtag in my case i use GtkTerm.
in debian is simply I open a root terminal and I write
apt-get install GtkTerm
in the same term i write
gtkterm
I use a root terminal because I don’t want waste time configuring /dev/ttSy* permissions
next step is configure port speed 9600,8N1
in GtkTerm menu select configuration/port and fill data boxes, in my case port is /dev/ttyUSB0 if you don’t know your port a dmesg output can be helpul.
now is time to plug powersounce on our fonera and see output.
must be something like this in our gtkterm
we need get access to redboot console you only need un plug and plug powersource to fonera and press continously ctrl+c until you see
RedBoot>
we need download ou firmware go to
http://downloads.openwrt.org/backfire/10.03.1/atheros/
and download these files
- openwrt-atheros-vmlinux.lzma
- openwrt-atheros-root.squashfs
search ftpd config for your distro
load -r -b %{FREEMEMLO} openwrt-atheros-vmlinux.lzma
fis init
fis create -e 0x80041000 -r 0x80041000 vmlinux.bin.l7
load -r -b %{FREEMEMLO} openwrt-atheros-root.squashfs
fis create rootfs
reset
fis load -l vmlinux.bin.l7
exec
“press enter”
reset
