We showed you how to downgrade A4 devices from iOS 5.1.1 to iOS 5.1 or lower and with the latest RedSnow 0.9.11b1, you can also downgrade A5 devices providing, of course, that you already saved your SHSH blobs for the firmware you want to downgrade to.
From the Dev Team’s blog:
You cannot downgrade without the personalized SHSH blobs for your device at that lower firmware. You need to have fetched those blobs while the signing window was open, using either Cydia’s built-in TSS@Home feature, or with TinyUmbrella. The new Restore screen of redsn0w lets you choose either remote blobs or local ones (for the earlier firmware). If you don’t know where TinyUmbrella put your blobs, TinyUmbrella has a button that will show you (copy them out of that folder and feed them to redsn0w).
The A5 downgrade method actually updates to the latests firmware before downgrading to the earlier one. This process updates your baseband to whatever is newest. DO NOT USE THIS METHOD IF YOU RELY ON UNOFFICIAL UNLOCKS of your iPhone 4S. Those who used the temporary SAM technique to unlock their iPhones to specific SIMs shouldn’t be affected by this baseband update.
This method can be fixed by Apple with a firmware update. It’s a (pleasant) mystery why they haven’t fixed it yet, because reverse-engineering of the restore ramdisk indicates they do know about it. It’s possibly too niche to bother to fix right now.
The least-tested devices with this method are the iPad2,3 and iPad 3,2 (because we don’t have those models). If you do and feel like experimenting, please let us know how it turns out in the comment section below!
This update involves a bunch of new redsn0w code. We recommend sticking to the previous 0.9.10b8b unless you’re specifically using this new feature, until all the bugs are worked out! (Note: If redsn0w gets stuck at the “Waiting for device†stage for more than 30 seconds, you’ve hit a pesky GUI bug…that will be fixed in an upcoming version!)
Download RedSnow 0.9.11b1 for Mac / Windows.
Update: iPhone Dev-team has just released Redsn0w 0.9.11 b2 to bring support for “9A406″ version of 5.0.1 for iPhone4S.
Download Redsnow 0.9.11 b2 for Mac
Download Redsnow 0.9.11 b2 for Windows
