In Recovery Mode, you can reflash the phone through iTunes using the BIOS .Ipsw file. This solves many problems.
To access Recovery Mode:
- Hold buttons simultaneously Home (black button with a square on the front side), and click Power (top). Ayfon will slide off the phone, then the screen goes off and covered with thin whitish lines. Do not release the button. After 15-25 seconds the image appears on the screen cable and icon iTunes. Now you can release the button.
- Connect the phone to your computer and open iTunes. In a message to check for updates click "Check Now". After that, iTunes will show the iPhone in recovery mode. For flashing hold Shift and click on Restore. In the file selection enter the BIOS file you want to use.
or
Try DFU Mode to restore Iphone

FU (Device Firmware Upgrade) mode is different from the Recovery Mode that acts to bypass the operating system directly to the iPhone and reflash firmware. This is an effective method and it allows us to solve problems such as inability to reflash via iTunes in Recovery Mode, inability to unlock the phone, etc. I would recommend to use it always, to avoid unnecessary trouble with flashing and unnecessary problems.
To enter DFU Mode:
- Quit iTunes;
- Connect your phone to the computer;
- Turn off your phone;
- Hold Power and Home buttons for exactly 10 seconds;
- Release the Power button but continue to hold Home until the computer displays a new USB-device. That may not happen - in this case, hold the Home for 20-30 seconds;
- The phone's screen will not be included in DFU Mode, do not wait;
- Open iTunes and follow the above instructions for flashing. Screen phone may appear white - this is normal.