Having issues downgrading or upgrading firmware?

[Lin]

1. Download the firmware file to which you want to downgrade your iPod Touch to, that is, if you want to downgrade iPod Touch 2G/3G 4.0.2 to iOS 4, then download iOS 4 firmware.

2. The second thing to do is to edit the Hosts file.

Windows-

• Open Notepad with administrator privileges. Right click in its icon and choose "Open as Administrator".
  
• Go to file>open and navigate to C:/Windows/System32/drivers/etc in Notepad and open the Hosts file.
  
• Add "74.208.105.171 gs.apple.com" at the end of the file and save the file.

Mac OS X-

• Navigate to Go->Go to Folder and enter "/etc".
  
• Using TextEdit, open up the Hosts file.
  
• Add ” 74.208.105.171 gs.apple.com ” at the and of the document, choose Save As, uncheck "If no extension is provide, use .txt" and save the file on the desktop.
  
• Replace the original Hosts file with the new one.
  

3. Now connect your iPod Touch to the computer.

4. Select your iPod Touch 2G/3G in iTunes.

5. Now enter into recovery mode by pressing the power and home buttons for 10 seconds and then release the power button but keep holding the home button until iTunes recognize your device in recovery mode.

6. Now hold the Shift Key in Windows or the Option Key in Mac OS X and click on the Restore button.

7. Browse to the required iOS 4 or 3.1.3 firmware file and select it to downgrade your iPod Touch firmware to that.

NOTE: This may not work for everyone