Found a loophole in Apple’s apticket system. Restored my iPad 2 to 5.0.1 from 5.1. Works on all A5 devices.
A5X devices will work too once Apple pushes a new firmware for it.
BTW, This cannot be applied to basebands. Only iOS itself.
It is currently possible to downgrade iPhone 3GS, iPhone 4, iPad 1, iPod touch 4G and iPod touch 3G from iOS 5.1 to iOS 5.0.1 using the SHSH blobs saved using TinyUmbrella or TinyCFW.
With this latest development, it means that iPhone 4S and iPad 2, which are powered by A5 chip and in the future the new iPad, which is powered by Apple’s A5X chip can be downgraded to the previous firmware versions as well.
So users will be able to downgrade to iOS 5.0.1 and enjoy the untethered jailbreak until the jailbreak for iOS 5.1 is released (Update on iOS 5.1 jailbreak available here). Update: We’re assuming that you will need SHSH blobs saved using TinyUmbrella to downgrade to iOS 5.0.1.
This is an amazing achievement as Apple had made it extremely difficult to downgrade to a previous iOS version with the release of iOS 5.0. iH8sn0w hasn’t mentioned when he plans to provide details on how to downgrade to a previous version.
Frequently asked Questions:
Here are answers to frequently asked questions:
1. Can I downgrade to iOS 5.1 to iOS 5.0.1 if I have iOS 5.0.1 SHSH blobs?
2. Can I downgrade to iOS 5.1 to iOS 5.0.1 if I don’t have iOS 5.0.1 SHSH blobs?
No, while iH8sn0w hasn’t provided the details it seems very (very) unlikely that you can downgrade to iOS 5.0.1 if you haven’t saved the SHSH blobs.
As always, we’ll let you know as soon as we’ve any further updates, so stay tuned at iPhone Hacks or join our Facebook Fan page or follow us on Twitter or add us on Google+ or subscribe to our RSS feed.
Update 1: Added the FAQ section.
Update 2: Added the note section for the answer to question 3 to avoid any confusion.
Update 3: Updated the FAQ section with information about iFaith.