So do you want to Jailbreak, Downgrade or just revive your iPhone, you will need to put in DFU mode
Follow the Steps Below
First Make Sure the Phone is Connected to the computer and Switched off.
- Hold the Power Button For 4-5 Seconds
- Then Press The Home button while not releasing the Power Button for 10 Seconds
- Now release the Power Button and Keep holding the Home button for 30 Seconds.
If the Following Steps Did not work the it usually means you went wrong somewhere and try again, also in the third and the Final step the iPhone usually goes int to DFU mode before 30 Seconds but if it doesn’t help then try keep holding the home button for 10-15 Seconds more.