Downgrade your iPhone 4 from iOS 6 to iOS 5.x using Redsn0w 0.9.15b2
The iPhone Dev Team has released back-to-back updates for Redsn0w within a matter of days. It is now possible to downgrade pre-A5 devices such as iPhone 4, iPhone 3GS and iPod touch 2G from Apple's latest iOS 6 platform to iOS 5.x.x using the saved SHSH blobs and the recently updated Redsn0w 0.9.15b2.
The new Redsn0w update brings significant bug-fixes to iPhone 3GS with older boot ROMs, besides incorporating an untethered jailbreak support for 3GS users with re-restore option. Another feature of the updated Redsn0w is the new direct restore capability for pre-A5 devices, which allows you to downgrade the device from iOS 6 to any iOS 5.x firmware, without dealing with host files, stitching, Pwned DFU, iTunes or other complicated methods of downgrading that were needed in the past.
SHSH blobs for the iOS 5.x.x firmware (the version of the firmware you want to restore) must be saved by using TinyUmbrella or the iPhone must be jailbroken on iOS 5.x.x with Cydia launched at least once. This is to ensure that caching of the SHSH blobs is enabled on its servers.
As the downgrade procedure restores your iPhone to iOS 5.x.x, you need to set up your iPhone from backup. The restore from backup feature supports only iOS 5.x.x or lower compatible backups.
Download the latest version of Redsn0w - 0.9.15b2 (Windows / Mac)
How to Downgrade Your iPhone 4 From iOS 6 to iOS 5.x Using Redsn0w
Make a folder on your desktop and name it as "Pwnage".
Copy the downloaded Redsn0w .zip file to the Pwnage folder on the desktop.
Download the firmware you want to restore your phone to (from here) and copy it to the Pwnage folder.
Extract the Redsn0w zip file to the Pwnage folder.
Right-click on the Redsn0w application-file in the Redsn0w folder (extracted earlier) and select "Run as administrator" from the pop-up menu.
Click Extras in the main menu and tap on Even more button. Now click Restore > IPSW (Restore menu). Finally, choose the IPSW firmware that you want to restore your phone back to from the pop-up window. Then click open.
Redsn0w prompts you to verify if you want to prevent baseband update process. Click Yes to confirm. This will preserve your older baseband settings.
Redsn0w will notify you that Pwned DFU mode is required for restoration process. Click OK.
Power off the device, connect it to the computer, and then click the Next button.
Follow the onscreen instructions in Redsn0w to enter DFU mode. Press and hold down the Home button and the Power button for 10 seconds. Release the Power button; but, continue holding the Home button until Redsn0w recognises the device.
Your phone will now be exploited with limera1n.
Redsn0w checks Cydia to confirm if you have the correct version of SHSH blobs saved. If the blobs fail to get detected automatically in Redsn0w, try clicking the Remote button for a rescan or click Local button to search for blobs on your computer.
At this point, Redsn0w prepares a system restore image and your device will be restored to the new firmware.
Once the device is restored, you will get a Restore successful message.
For further assistance, check out the video tutorial below [Courtesy: iDownloadblog]: