Follow the steps explained below to Upgrade iPhone 4 to iOS 5 firmware . Latest version of Redsn0w 0.9.9b5 is used here to Preserve Baseband and create custom ipsw used for upgrading to iOS 5 without changing original baseband . This tutorial will be useful for those who rely on Ultrasn0w or Gevey Sim based unlock .
Note : This tutorial will not jailbreak your iPhone 4 . Redsnow 0.9.9b5 was not available for Windows at the time of writing this tutorial . Windows users can use Snowbreeze iOS 5 Upgrade Tutorial to preserve baseband.
Steps to Upgrade iPhone 4 to iOS 5 :
- Download iOS 5 ipsw
- Download iTunes 10.5
- Download Redsnow for iOS 5 Jailbreak
- Launch Redsnow and connect your device with the USB cable
- Click on Extras button and select Custom IPSW button
- Now browse to the iOS 5 ipsw downloaded in Step 1
- Allow Redsn0w to process the custom firmware .
- After the firmware is create you to select Pwned DFU button to proceed and restore to custom firmware created before .
- Redsnow will now ask you to put your device into DFU mode . For that you have to press and hold both home and power buttons for 10 seconds and release power button and keep holding home button for another 10 seconds . This will put your device in DFU mode . Redsnow will now do its work and put your phone on Pwned DFU mode .
- Launch iTunes and it will now see your device is in recovery mode . Press OPTION button on Mac / SHIFT button on Windows keyboard and select Restore and browse to the new IPSW file created above .
- iTunes will now restore your device to new custom iOS 5 firmware .