This is my attempt at a noob friendly guide to flashing your Fon+ with Jasager in Windows XP (this is also my first post). I have amalgamated aspects of DigiNinja's and Darren's guides to solve the problem of flashing the awkward UK Fon+ (check the model number FON2201C-UK); although following this guide should flash Fon+'s from around the world.
If you get stuck at any point I would recommend reading Darren's Hak5 step-by-step forum post (excellent show guys) or DigiNinja's guide to installing Jasager.
So here goes...
USB to Serial Cable
As you probably know the IP on the UK Fon+ is set to 0.0.0.0 and therefore can only be flashed using a serial cable. Bad times :( . There is an excellent guide on fashioning your own cable posted by DigiNinja on his website. I bought a Kycera cable from eBay and soldered the connections to single pin computer cables from Maplins, much easier than I thought.
Connect to RedBoot
Now you need to connect to your Fon+ through Putty to something called RedBoot onboard the Fon+.
First you need to find the COM Windows XP assigns. Right-click on 'My Computer' and choose 'Manage'. Navigate to 'Device Manager' click on 'Ports (COM & LPT)', you should see your cable and the COM port it has been assigned..
Open Putty and ensure that your 'Serial' settings are set to 9600, 8 and 1. Be sure to set 'Flow Control' to 'None'! Click 'Open'.
Insert the power to your Fon+ and immediately press Ctrl + c to interrupt the device startup. You will notice that the IP for the device is set to 0.0.0.0. Not for long.
Change the Fon+ IP
To change the IP enter the following into the RedBoot session you just opened, you will need to input anything in bold (<Return> means press the enter key):
Run script at boot: true <Return>
Enter script, terminate with empty line
Boot script timeout (1000ms resolution): 2 <Return>
Use BOOTP for network configuration: false <Return>
Gateway IP address: <Return>
Local IP address: 192.168.1.1
Local IP address mask: 255.255.255.0
Default server IP address: 192.168.1.254
Console baud rate: 9600 <Return>
GDB connection port: 9000 <Return>
Force console for special debug messages: false <Return>
Network debug at boot time: false <Return>
Update RedBoot non-volatile configuration - continue (y/n)? y
... Erase from 0xa87e0000-0xa87f0000: .
... Program from 0x80ff0000-0x81000000 at 0xa87e0000: .
Now power off the Fon+. Connect Ethernet between your computer and the Fon+.
Flash UK Fon+ with Jasager Firmware
Download the 'Jasager Firmware 1.0' from DigiNinja. Extract the .tar from the .bz2 file using 7-zip; then extract the resulting .squashfs and .lzma files from the .tar - again using 7-zip.
Now we are going to use Freifunk Ap51 EasyFlash (I downloaded ap51-flash-gui-1.0-42.exe) which make flashing the Fon+ super simple.
In the GUI under 'Rootfs' check 'Use external file' and browse to 'openwrt-atheros-root.squashfs' you just extracted. Under 'Kernel' check 'Use external file' and browse to 'openwrt-atheros-vmlinux.lzma'. Select your Ethernet interface from the 'Interface' drop-down.
Power on the Fon+ and immediately click 'Go' in EasyFlash. The flashing process takes almost 20 minutes.
Image from Darren's post.
Set Your Password in Telnet
Using Putty select Telnet and Telnet over to 192.168.1.1 type passwd and set your password twice; I recommend ilovepineapples!
Go to your favourite browser and enter 192.168.1.1:1471. Enter root as the user and your password in the password field. Well done, you successfully flashed your UK Fon+ !
EDIT: I compiled my 'how to' after 12 hours of experimentation with several methods; if I have missed any steps or made a mistake please reply to this thread and I will make adjustments accordingly. Thanks.