Downgrade An iPhone 4S or iPad 2 On Windows [TUTORIAL]
With the tutorial here, you can downgrade all A5 devices. That includes the iPad 2, iPhone 4S and the New iPad (third generation iPad).
Here is the video, showing the procedure:
You should remember that this method only works for A5 devices. You will need your SHSH blobs saved locally or on Cydia in order to downgrade. If you are relying on a software unlock or SIM interposer, beware! This method will update your baseband, and you could permanently lose your unlock.
Now we explain the procedure step by step:
STEP 1 – Download RedSn0w 0.9.11b1.
STEP 2 – If you are not having the necessary firmware available on your computer, download iOS 5.0.1 (9A405) for your device and iOS 5.1.1 for you device as well.
STEP 3 – Run RedSn0w as an administrator and click Extras > Even more > Restore. After this, under the IPSW section, you need to click the IPSW button and select your iOS 5.0.1 (9A405) firmware. Once verified, select your iOS 5.1.1 firmware.
STEP 4 – After your firmware has been verified, you should click the Remote button under the Blobs section. This will pull your blobs directly from Cydia if you have jailbroken and saved your blobs to Cydia in the past. If you have not done this, you need to select Local and point to you blobs on your computer if you saved them with a tool like TinyUmbrella. If you have not saved your blobs, you cannot downgrade.
STEP 5 – Now be patient and let your device restore completely. It will start by installing a hacked 5.1.1 firmware, followed by the downgraded iOS 5.0.1 firmware. This takes about 10 minutes.
Once these steps are complete, go through your device’s initial setup. Now, you should be back on iOS 5.0.1. Now you can use the Corona-A5 untethered jailbreak if you wish to do so.
Source: iDownload Blog