Therefore you are searching for a working solution to bring your existing version iOS back to 5.0.1. Fortunately you can!
But halt yourself, before thinking into downgrade your A5 device, there is one single requirement you need to meet. SHSH blobs is needed, in case you have saved it using tools like TinyUmbrella or stored on Cydia's server. Then you are all set.
And as for those who are probably have stored SHSH blobs on Cydia, you can check it to find out whether you have it already. See the below image to know exactly the reference Cydia placed whether your iOS SHSH blobs is there. Afterward you can restore it, and with the help of Redsn0w.
Now it is time to downgrade iOS 5.1 or iOS 5.1.1 to iOS 5.0.1. Firstly get the following requirements before taking any actions.
- Download Redsn0w 0.9.11b1 Windows / OS X.
- Download iOS 5.1.1 based on your device.
- Download iOS 5.0.1 based on your device.
Downgrade iOS 5.1.1 or iOS 5.1 to iOS 5.0.1 for iPhone 4s, iPad 2 and iPad 3.
Step 1: Now launch Redsn0w 0.9.11b1. And then click Extras, in the next Window select Even More at the screen's bottom.
Step 3: Now click Restore, and then continue with clicking IPSW and then select iOS 5.0.1 firmware on your PC, when you are prompted, select your existing firmware versions whether it is iOS 5.1.1 or 5.1.
Step 4: When you've done selecting your firmware version, now it's time to load up the SHSH blobs. Remember: if your iOS 5.0.1 is not jailbroken, you must select LOCAL to find your blobs via TinyUmbrella. But if the iOS 5.0.1 already jailbroken, then select REMOTE for Redsn0w to start loading them for you.
Step 5:Now Redsn0w will place your device into Recovery Mode, and continue its step to restore.
Step 6: Congratulation, you have downgraded your iOS to iOS 5.0.1, you should see this wonderful message when all the process is done.
Step 7: Done!
Via Cydia Help.
Update: You don't need to downgrade your iOS 5.1.1, but keep it and download Absinthe 2.0 for Windows and Mac.