1. Choose correct flash file(s).
2. If you have PIT file chosen, then you must check "Repartition" option.
3. Check flashing options if needed (Repartition, EFS clear, Boot update).
4. Power on phone in download mode:
 - device must be powered off;
 - press power button more than 7 seconds;
 - when "Rebooting..." message will appear, short press power button 3 times;
 - in "Reboot menu" select "Download(USB)" (move = short pressing, select = long pressing).
5. Connect phone to PC with USB cable, install drivers if needed.
6. Press "Flash" button.