Phone [Q] how to unlock celkon A8+ bootloader ?

i have celkon devise it is running android 4.0.1 , i attempted to root it the root was successful and had no problem admin access but it did not
unlock the boot loader of my mobile . i want to unlock my mobile's boot loader please help me

Additional info :-
when i press powerbutton and volume up
it says spreadtrum factory test phone test factory use

and gives me these options :-

1) full phone test

2) view phone test result

3) item test

4) bt eut

5) exit

but these options are not related to bootloader please help me to unlock my bootloader