9)For Windows : Hold the shift key and then hit the restore button.

8)For a Mac : Hold Option key and then hit Restore button.7)Click on ‘Ok’ to the prompt displayed.6)The iPhone will show you a blank screen (black).

Continue holding the Home button until iTunes pops up a message saying that it has detected an iPhone in recovery mode. 5)After exactly 10 seconds release the Power button.Press and hold the Home button and the Power button at the same time for 10 seconds. If not, watch this quick video and pay close attention to the steps to achieve DFU mode. 3)If you are aware of DFU mode, proceed further.If not jailbroken already, continue to the next step (3). 2)If your iPhone is already jailbroken (if you see Cydia on your iPhone!), put your device in Restore mode (Turn iPhone off, keep holding Home button while you plug it in to your computer).1)Launch iTunes and connect the iPhone to your Mac / Windows computer.ipsw or else, it will give you an invalid firmware error). You should now have the respective firmware file with an extension.Step 3) Restore the firmware in iTunes 9.x

Download HJSplit to join both the files – Link for Windows Computers here and Macs here.

They need a special opensource (free) software HJSplit to join.

The files downloaded above have an extension.

iPhone 2G 3.1.2 Custom Firmware Activated for Other Carriers Part 2.

iPhone 2G 3.1.2 Custom Firmware Activated for Other Carriers Part 1.

Download the following files ONLY if you don’t have an iPhone contract (T-Mobile and others…).

iPhone 2G 3.1.2 Custom Firmware Not Activated Official Carriers Part 2.

iPhone 2G 3.1.2 Custom Firmware Not Activated Official Carriers Part 1.

Download the following files ONLY if you have an Official iPhone contract with your cell carrier (ATT and others….).

ITunes 12.12.10 for apple instal