This post will show you how to downgrade the iPhone 4S, iPad 2 and The New iPad from iOS 5.1.1 or higher to 5.1 and 5.0.1.
It is important you have your SHSH blobs on file for the iOS version you want to downgrade to. If you don’t have your SHSH blobs on file for the iOS version you want to downgrade to, you will not be able to downgrade. You can check which SHSH blobs you have on file by launching Cydia and looking at the top of the Cydia homepage where it lists all your saved SHSH blobs.
1. Right click Redsn0w and set compatibility to windows XP (service pack 2) if you are on Windows 7 or Windows Vista and run as administrator.
2. Connect your iDevice to the Computer and turn it off; after you have done this run Redsn0w (If it isn’t already connected).
7. Just sit back and wait for Redsn0w to work it’s magic. The process can take from 3 – 6 minutes to complete depending on you device and computer.
11. That’s it your device should be on the firmware that you selected to downgrade to.
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