How to Downgrade iOS 5.1 to 5.0.1 for iPhone/iPad?
Lately, Redsnow has upgraded to support for the degradation of A5-equipped hardware. The downgrading process is mainly designed for those users who have been enjoying an untethered jailbroken iOS 5.0.1 properly, but once back the iOS devices to the state that has not been jailbroken because of accidentally upgrading to 5.1\5.1.1 firmware.
Since the process of downloading to iOS 5.0.1 on a Mac and Windows are roughly the same, so here we come with the tutorial of how to downgrade iOS 5.1 to 5.0.1 on Mac with Redsnow 0.9.11b1 to tell you the details. What needs to note before the degradation is that you must have the SHSH blobs of the old firmware, such as the 5.0.1SHSH, or SHSH 5. If you have anyone of these two, then, you can just follow the coming up tutorial to downgrade iOS 5.1 on your Mac now!
Note: This downgrade tutorial is only able to work on the iPhone 4S, iPad 2 and the new iPad which has A5-equipped. For the iOS devices with A4 and below, this step-by-step guide is unbefitting.
Details of How to Downgrade iOS 5.1 to 5.0.1 on Mac
First: In order to go through the entire degradation of A5-equipped hardware perfectly, you should first download the latest version of the RedSn0w0.9.11b1 for Mac and get both the 5.0.1firmware and 5.1.1firmware on your Mac.
Secondly: Start the device into DFU mode.
Thirdly: Run the formerly downloaded RedSn0w 0.9.11b1 on your Mac. It will determine whether your connected device was into DFU mode, just have a quick glimpse of it. You should then choose the "Extras> Even more> Restore" and click the IPSW in the following windows. Go to the "Firmware" section to find the just downloaded two IPSW firmwares, namely 5.0.1 and5.1.1.
Fourthly: After verifying that two firmwares, then you need to use the SHSH blobs you've once saved. If you have previously backed up using Cydia, you can rightly hit "Remote" to connect to the Cydia server so as to access remote SHSH blobs. If you once used the tiny umbrella for the backup, then you should click on the Local to look for the SHSH blobs locally on the computer.
Fifthly: Once verified the SHSH, you can just leave all the next things to the RedSn0w. It will complete the downgrade to 5.0.1 thoroughly. And here we will not specifically explain how it works downgrade.
Finally: Once you see the "Restore successful" notice, then you have triumphantly downgraded your iOS 5.1 to 5.0.1.
Ok, you are able to have fun with the 5.0.1 on your iPhone 4S, iPad 2 or the new iPad again now!