steps:
Put the phone in FastBoot Mode:
1. Remove SD and SIM cards from the phone
2. Power phone OFF
3. Press and hold "Vol-" and insert USB cable
4. Wait until the phone enter in FastBoot Mode
Put the phone in FastBoot Mode:
1. Remove SD and SIM cards from the phone
2. Power phone OFF
3. Press and hold "Vol-" and insert USB cable
4. Wait until the phone enter in FastBoot Mode