Placing iPhone 4S in DFU Mode
To restore the iPhone 4S to a factory fresh state we need to place the iPhone 4S into Recovery Mode. However, under certain circumstances, Recovery Mode will not work. In that case you need to put your phone in DFU (Device Firmware Upload) mode.
Caution: it is recommended that you back up all data via iTunes before continuing.
How to enter DFU Mode on your iPhone 4S:
- Open iTunes and connect your iPhone 4S via USB cable.
- Make sure to turn off the phone using the On/Off Button.
- Now, hold down the Home Button and Sleep/Wake Button at the same time.
- Continue holding these buttons for 10 seconds then release the Sleep/Wake Button but keep holding the Home Button until the iTunes shows you the following message:
"iTunes has detected an iPhone 4S in Recovery Mode"
- Follow the on screen instructions. iTunes will guide you through the rest of the process.