Here’s how to revert to a previous firmware version on your iPod Touch (iPhone?), even when apple states in it’s release notes for the new (beta) firmware that it’s not possible to revert 😉
The trick is to correctly enter your iPod into the DFU (Device Firmware Update) mode.
- start iTunes
- connect your iPod to your computer
- press the power button and home button down for at 10 seconds
- release the power button and?keep the home button pressed until iTunes shows a message that it has found an iPod in recovery mode
- option – click on the restore button in iTunes
- select your firmware file (in my case 2.2.1), if you can’t find it, download it here and rename the .zip file into .ipsw, then select it in iTunes
- the firmware update starts, but keep patient! (sometimes it seems nothing happens, but wait, you will see it does)