Apple has released iOS 4.3.1 for iPhone 4, iPhone 3GS, iPod touch 3G, iPod touch 4G, iPad 2, and iPad. Now simply follow the step by step instructions posted below using which you can downgrade iOS 4.3.1 to 4.3, 4.2.1, 4.1 on iPhone 4, 3GS, iPod touch, iPad 2, iPad on iPhone 4, iPhone 3GS, iPod touch, iPad. You should remember you must have SHSH blobs saved for the respective firmware you want to downgrade. Now follow the steps carefully.
How to Downgrade iOS 4.3.1 to 4.3, 4.2.1, 4.1 on iPhone 4, 3GS, iPod touch, iPad 2, iPad
STEP 1. First you have to download the required old ipsw firmware files.
STEP 2. Now you have to put your iOS device into DFU mode by following the steps posted below.
- Simply connect your iOS device to your computer.
- Launch iTunes, then hold down both the Home and Power button simultaneously for 10 seconds.
- Now release Power button and keep holding the Home button until a new USB device is recognized by your computer.
- Now your iPhone, iPod touch or iPad will be recognized by iTunes.
STEP 3. Now we have to change the address to Saurik’s server. For this simply follow the steps.
- First navigate to the path c:\windows\system32\drivers\etc\ and locate “hosts” file.
- Now you have to open the “hosts” file in TextEdit (for Mac OS X) or Notepad (for Windows) and add the following:
Now save the file.
STEP 4. Launch iTunes and from the sidebar in iTunes, click on your iOS device icon. Now simply press and hold Left “Shift” button on Windows or left “alt” (option) button on Mac OS X. Then simply click on “Restore” button and then release the button.
Now iTunes will ask you to choose the location for your iOS 4.3, iOS 4.2.1 or 4.1 firmware file. Then simply select the desired ipsw file and click on “Open” in order to restore your iPhone, iPod touch or iPad.
Now you have to wait for some time until iTunes installs the requested firmware on your iPhone, iPod touch or iPad. At this time you will be able to see a progress bar indicating installation progress on the screen of your iPhone, iPod touch or iPad. After completed your iPhone, iPod touch or iPad will be restarted automatically. iTunes might show 1013 error at some time. Simply ignore this message.
Incase of this error, your iPhone, iPod touch or iPad will be stuck in Recovery Mode, “Connect to iTunes” screen will be shown.
Now you have to download TinyUmbrella (Mac / Windows) and run it. Now simply click on “Exit Recovery” button in order to exit your iPhone, iPod touch or iPad from Recovery Mode. Now your iPhone, iPod touch or iPad will be restarted.
That’s it. In this way you can downgrade iOS 4.3.1 to 4.3, 4.2.1, 4.1 on iPhone 4, 3GS, iPod touch, iPad 2, iPad. Now you can unlock and jailbreak your iPhone, iPod touch or iPad on iOS 4.2.1. You can follow the step by step instructions posted here to jailbbreak your iPhone, iPod touch or iPad on iOS 4.2.1. Click here to download iOS 4.1, Click here to download iOS 4.2.1 for iPhone, iPod touch and iPad. Click here to download iTunes 10.1.1. Click here to download iOS 4.3.
In order to receive future updates from Apple via iTunes you must have to remove 18.104.22.168 gs.apple.com line from the host file. If you found any difficulty in following the above steps then feel free to ask in the comment section below. [Via]