First there is some requirements for flashing mobile.
Requirements:
- Android mobile (50-60% charge is mendateory)
- USB cables
- SP-Flash software
- Scatter file (you should download according to your mobile model)
Steps how to use flash tool for flashing your mobile
Remove the battery from your phone and back it again with out formating your phoneNow Run SP-Flash Tool (Run as Administrator)
Now you will see this type of windows.

Now you should click on Scatter loading button as shown in the figure below.

Now you should choose your scatter file after choosing scatter file click open.(As in figure below).

Now click download to start flashing.

Now press volume Up &volume Down key and connect your device to your computer using USB Cable.
Finally After completing green sign is appears on your mobile screen.
Download Your SP-FLASH TOOLS