- Turn off Find my iPhone & disable passcode lock via the Settings app. (Settings > iCloud > Find my iPhone).
- Launch iTunes & connect your iPhone, iPad & iPod Touch using data cable to your computer.
- Hold the Alt/Option key on the Mac or Shift Key in Windows on your keyboard and click on the Check for Update option, instead of restoring. Important: Please note that holding the Alt/Option key on the Mac or Shift Key in Windows is very important
because then iTunes will update your device to iOS 9.1, so be careful.
- Now Select the iOS 9.0.2 ipsw file you had downloaded earlier.
- iTunes will inform that it will update your iOS device to iOS 9.0.2 and will verify the update with Apple.
- Click Update.
- iTunes will now install iOS 9.0.2 on your device.
That’s it. Your device should now be successfully upgraded to iOS 9.0.2.
follow this link