Uzip FlashTools, and Click on Flash_tool.exe
Select "scatter-Loading" and search MT6580_Android_scatter.txt in ROM
Wait file to be added into Flash Tool
Select "Download Only" or if upgrade "Firmware upgrade"
Turn off your phone, remove the battery (if the battery is removable) and replace it after some seconds (and don't turn on the phone).
Press “Download” button to start
and connect your phone into the computer via USB data cable.
The process will start and a red progress bar will appear after color purple, yellow.
And green circles display
Completed