- iPod touch 3G
- iPod touch 4G
- AppleTV 2G
First a word of advice: ultrasn0w users don’t update yet! ultrasn0w is not yet compatible with 4.3.1.
Download iOS 4.3.1 for your device
Run PwnageTool, select "Expert Mode" and choose your device.
Select "Browse for IPSW..." and select the downloaded firmware for your device.
PwnageTool will automatically active your phone and prevent Baseband update so you can just click "Build".
Save the custom firmware somewhere you find it later (desktop) and wait a few minutes.
Now follow the instructions on the screen.
If it doesn't work on the first try, just do it again.
If you've done it right you should see this screen.
Now open iTunes and click "Restore" while holding the alt key.
A file dialog opens, select the custom firmware you saved on your desktop.
Select "Restore" and wait till it's done.
After that iTunes will restore you're last backup.
Now we are done, enjoy your jailbroken 4.3.1 device :)
Error 1601 during restore
If you are updating from a jailbroken 4.2.1 and u used tiny umbrella, remove the
line from your /etc/hosts file and restart iTunes.
Do the same procedure again but this time uncheck "active phone" in Pwnagetool.
Thanks to the iPhone Dev Team