[Guide] How to downgrade iOS 5.0.1 to 4.3.x

Apple recently released a new updated to iOS which was aimed to fix battery issues which have been plaguing users since the release of iOS 5. Some users have continued to face battery issues after updated to iOS 5.0.1.

If you are one of the users who have updated to iOS 5.0.1 and want to downgrade back to an older version, you can read our guide which follows...

NOTE - Your device should have been previously jailbroken on iOS 4.x an your SHSH blobs of the version you want to downgrade to should be saved.

NOTE - You should be able to downgrade to iOS 5.0 until Apple stops signing that version. Apple is planning to block the SHSH blob saving method with iOS 5. So once Apple stops signing iOS 5, you wont be able to downgrade to it from iOS 5.x even if you have the iOS 5 SHSH blob saved.

NOTE - This guide is not applicable for the iPhone 4S. There is no known jailbreak available for this device at the time this guide was written.

1. Download the version of iOS you wish to downgrade to, remember that you should have the SHSH saved for that particular version.
• iOS 5.0
• iOS 4.3.5
• iOS 4.3.4
• iOS 4.3.3
  
2. Connect your device to your computer using the USB cable and boot into DFU Mode
• Turn device off
• Press and hold Power + Home buttons for 10 seconds
• Release the Power button but keep holding the Home button for an extra 10 seconds.
• The screen will blink and go blank for a second which confirms you are in DFU.
3. Navigate to your hosts file and make a backup of it
• Windows - Windows > System 32 > drivers > etc
• Mac OS - /etc (Type Open /etc in the terminal)
4. Open the hosts file using a text editor
5. Add the following code to the hosts file and save it.
• 74.208.105.171 gs.apple.com
6. Open iTunes, Choose your device from the sidebar. 
• Hold Shift (Windows) or Alt (Mac OS) and click on Restore.
• When propmted, browse and select the firmware file you downloaded in Step 1
• If you get any error messages ( Error 10xx) 
• Download TinyUmbrella or Fix Recovery
• Click Exit Recovery and you should get out of the error.

And you are all done.

If you followed the steps correctly you will have successfully downgraded from iOS 5.0.1 to iOS 4.3.x. You can now jailbreak your device under the new firmware using a method of your choice.

You can now restore the hosts file you backed up in Step 3