GPS problems? Email retrieval issues? Accidentally upgraded your iPhone OS, only to find that you can’t unlock the new firmware? Whatever problems you might be having with your newly upgraded iPhone or iPhone 3G might be solved with a quick iPhone OS downgrade. It’s not the most convenient or efficient method of dealing with iPhone and iPhone 3G problems, but an iPhone OS downgrade is a viable last-resort solution that might just keep you from pulling out your hair in frustration. So, just how do you go about downgrading the iPhone OS on that precious little handset of yours? Keep reading.
1. First you’ll want to make sure you’re running iTunes 7.5
* If you have a newer version, go ahead and uninstall that version of iTunes
* Download iTunes 7.5 here
* Install iTunes 7.5
2. Download an older version of the iPhone OS to your desktop
* If you’re downgrading from iPhone 2.1 OS, you’ll probably want to go with iPhone 2.0.2 OS
* If you’re downgrading from iPhone OS 2.0.2/2.0.1/2.0.0, you’ll probably want to downgrade to iPhone OS 1.1.4
* Find previous iPhone OS versions here.
3. With the older version of iTunes installed, connect your iPhone or iPhone 3G to iTunes via the USB data cable
4. Reboot your iPhone into DFU restore mode
* Hold down the “Power” and “Home” buttons simultaneously until your iPhone turns off (ignore the “Slide to Power Off” prompt)
* When your iPhone turns off, release the “Power” button but keep holding that “Home” button
* Hold the “Home” button for a good 10 seconds
* iTunes will recognize your iPhone in restore mode and prompt you to restore the iPhone before using it
5. Force your iPhone or iPhone 3G to restore itself using the older iPhone OS that you downloaded previously
* Mac - hold down the “Option” key as you mouse-click on “Restore” button in iTunes
* PC - hold down the “Shift” key as you left-click on the “Restore” button in iTunes
6. Select the older iPhone OS file that you downloaded to your desktop
7. Enjoy your newly downgraded iPhone or iPhone 3G!
* Ignore any 1011, 1013, 1015 errors
* Errors like 1601, 1602, 1600 require that you put your iPhone into DFU restore mode again and force-restore again (start at Step 4)
