Apple releases new iOS version every now and then to add features fix the bugs/exploits over the previous iOS version which for jailbreakers isn’t quite healthy. If you’re looking to downgrade to a previous version of iOS to recover your jailbreak priveleges and have an A4 iOS device then see below for step by step instructions through which you can successfully downgrade from iOS 5.1.1 to below versions using latest version of RedSnow.
1. You should have saved the SHSH+APTicket for the firmware version you are downgrading your iOS device to.
2. Only A4 devices (iPhone 4-3GS, iPad, iPod Touch 4G and below) are applicable to the below mentioned guide.
3. Unlockers relying on older basebands must first create a custom firmware without the upgraded baseband using Redsn0w for the firmware they are downgrading to.
4. Latest RedSnow version (0.9.10b8b) [Download Link]
How To Downgrade A4 iPhone-iPad-iPod Touch Running iOS 5.1.1 To iOS 5.1-5.0.1-5.0
Step 1: Backup your device’s data via iTunes or iCloud.
Step 2: Launch Redsn0w and connect your device to your PC or Mac via USB.
Step 3: Click on Extras, then click on SHSH blobs, then Stitch.
Step 4: Select IPSW to which you want to downgrade to, and then point Redsn0w to the .plist file containing the SHSH blobs and APTicket. If these files are stored in Cydia, the option will be greyed out but will become available when the device is in DFU mode.
Step 5: Put your device in DFU mode, click on Cydia if the aforementioned files are not stored locally, and Redsn0w will save the new stitched IPSW file.
Step 6: Place your device into Pwned DFU Mode. From Redsn0w’s main screen, click on Extras > Pwned DFU and follow the on-screen instructions.
Step 7: If you’re a Windows user, simply head over to Windows > System 32 > drivers > etc. On OS X, head over to etc.
Using any text editor, you are going to add the following line at the end of the hosts file to spoof the device:
Step 8: Finally, launch iTunes, hold down the left SHIFT key (if you’re on Windows), or hold down the left ALT key (if you’re on OS X), and click on the Restore button, select the stitched IPSW file and restore.
That’s it!, now you can easily jailbreak you iOS device using the same methods you used before to perform the untethered jailbreak on your device.