How can I downgrade from iPhone firmware 3.1?
As we reported earlier, many iPhone users have encountered problems with the iPhone 3.1 firmware upgrade. Until Apple comes out with fixes for these bugs, the solution may be a downgrade to earlier software versions.
If you're having problems with the iPhone 3.1 update, try this restore to downgrade to iPhone OS 3.0.1:
- Download the correct iPhone 3.0.1 IPSW file for your iPhone:
http://www.quickpwn.com/2009/07/iphone-3-0-1.html has the IPSW files from Apple under "iPhone 3.0.1 Download Links."
- Make sure your iPhone is connected to the computer.
- Open iTunes, then hold down "Option" and select "Restore" on your Mac (Shift and Restore in Windows) when your iPhone mounts.
- Choose the downloaded 3.0.1 IPSW file.
- This will restore your iPhone to OS 3.0.1.
- Now you can restore to your latest iPhone backup.
To downgrade your iTunes to version 8 or 7.7 see instructions here.