Step-by-step Tutorial: How to create custom firmware for iPhone 4 using RedSn0w 0.9.10 (Windows) [iOS 5.0.1]
UPDATE: Apple released iOS 5.1 that is only tethered jailbreakable with redsn0w. Apple has stopped signing iOS 5.0.1, so you can NOT restore to 5.0.1 any more (both original and custom), unless you have saved your SHSH keys for 5.0.1. If you are on 5.0.1 you can jailbreak with redsn0w.
This is step-by-step instructions on how to create custom firmware, update to iOS 5.0.1 and perform untethered jailbreak of youriPhone 4 using RedSn0w 0.9.10 for Windows. It will also preserve baseband version if you need carrier unlock.
Untethered jailbreak means that each time you restart your device you will NOT need to connect it to a computer and run utilities.
Important: Please, consider reading our Jailbreak & Unlock FAQ, if you have other device or firmware and especially if you have questions or troubles.
Please think first, before you do something.
Create a folder on your desktop (or any other folder on your computer) called Pwnage
The latest version RedSn0w 0.9.10b4 from here. Save it in the Pwnage folder.
Extract the redsn0w executable from the RedSn0w zip file into the same folder.
Connect your iPhone 4 to the computer and launch iTunes.
Select your iPhone from the list of devices on the left. Create a backup by right-clicking on iPhone name in Devices (iTunes left pane) and choosing Back Up.
Open the Pwnage folder and launch the redsn0w application from the redsn0w folder we extracted earlier.
On Windows Vista or Windows 7 right click the executable and set it to run as administrator in Windows Vista/XP compatibility mode.
Once RedSn0w opens click the Extras button.
Then press Custom IPSW button.
Select IPWS dialog will appear. Navigate to Pwnage folder and select firmware you have downloaded on Step 1.
Redsn0w will start creating custom firmware. It might take some time, be patient.
Once the process is done you will see the following dialog box:
Press Pwned DFU button.
Please plug your iPhone 4 into the computer and make sure its OFF then click the Next button
RedSn0w will now guide you through the steps to get into DFU mode.
1. Hold down Power button for 3 seconds.
2. Without releasing Power button, hold down both the Home button and the Power button for 10 seconds.
3. Release the Power button and continue holding the Home button until RedSn0w detects the device (~15 seconds).
If you have problems try again.
Redsn0w will put iPhone into special state, so you can restore to the custom firmware in iTunes and bypass all errors.
Once this is complete you will be notified that RedSn0w is done.
Open iTunes. You will see a message that iPhone is in special state. Just click OK button.
Now hold down Option (Mac)or Shift (Windows) key and click the Restore button.
Navigate to the Pwnage folder using the dialog window that appears. Select the custom IPSW that was created and click the Choose button. Your custom firmware will have the following name: NO_BB_iPhone3,1_5.0.1_9A405_Restore.ipsw.
iTunes will now restore the firmware on your iPhone. This can also take up to 10 minutes. Once done you will be rebooted into jailbroken iOS 5.0.1!
iTunes will ask if you want to setup your iPhone as a new device or restore from the backup. Choose Restore from Backup if you want to preserve your contacts and other information.
Now you have iOS 5.0.1 installed and preserved modem version. Now you can jailbreak using our tutorial here (go to step 3, since you're already on 5.0.1).
When your iPhone has restarted you can run Cydia. Let it do all the necessary updates.
To have access to the root file system of your iPhone (via file managers like iFunBox or iPhone Explorer) install application called afc2add in Cydia.
If you need carrier unlock – install ultrasn0w via Cydia (if you do not need carrier unlock skip this step). Ultrasn0w supports iPhone 4 baseband 01.59.00 and iPhone 3G/3GS basebands 04.26.08, 05.11.07, 05.12.01, 05.13.04, 06.15.00.
Go to Manage than click Sources.
If you see repository http://repo666.ultrasn0w.com, go to step 8.
Click Edit button in the top right corner.
Then click Add button in the top left corner.
Type http://repo666.ultrasn0w.com and click Add Source.
Then click Done.
Click on on newly created repository http://repo666.ultrasn0w.com.
Click on ultrasn0w and hit Install button in the top right. (if you do not see ultrasn0w, go to Search and find it there).