[Weber Rex]

 How about  VIVO Y71  oem boatloader ?! unlock  
i need help if i open  my oem bootloader unlock  .boot. img installing  will be ez  
installing  magisk  root :not ini root mob phone !no twrp!! i   but this 

fastboot getvar unlocked..
unlock :no   come on ok next
fastboot oem unlock-go..
unlock :no    come on Virgin vivo 
fastboot flashing unlock..
unlock :no    I'll be back 

[X3non]

 How about  VIVO Y71  oem boatloader ?! unlock  
i need help if i open  my oem bootloader unlock  .boot. img installing  will be ez  
installing  magisk  root :not ini root mob phone !no twrp!! i   but this 

fastboot getvar unlocked..
unlock :no   come on ok next
fastboot oem unlock-go..
unlock :no    come on Virgin vivo 
fastboot flashing unlock..
unlock :no    I'll be back 

what's the error message you get when you try unlocking bootloader? 
did you enable OEM-unlock in settings on the phone?

do you have the firmware for your device?
if yes, then patch stock boot using magisk then try using custom flasher in miracle box @ https://www.hovatek.com/forum/thread-26213.html
ensure to select your vivo model from the drop down list, write only patched_boot

[Weber Rex]

about the setting in phone i already unlock oem + USB debugging ? then i use adb to fastboot.
_:> fastboot getvar unlocked..
>unlock :no
_:>fastboot oem unlock-go..
> error unknown cmd
_:>fastboot flashing unlock..
>error unknown cmd

if my bootloader oem unlock i can install pacth_boot.img = my root is done ...
i need to try about yr suggestion try using custom flasher in miracle box ,is there any link i can know more about it sir! any videos ?
tq for replay my thread sir tq ??

[X3non]

...
if my bootloader oem unlock i can install pacth_boot.img = my root is done ...
i need to try about yr suggestion try using custom flasher in miracle box ,is there any link i can know more about it sir! any videos ?
tq for replay my thread sir tq ??

check the link in my previous reply. there's a video guide in the link too

[Weber Rex]

there are more i need to learn about (miracle thunder) i use now.
i follow yr video
back up my firmware in zip ..
i get my boot. img
but i need to know how to unblock bootloader . ever time i try
device not found or time out...
?i m newbi don't know how pls help

[X3non]

there are  more i need to learn  about  (miracle thunder) i use  now.  
 i follow  yr video  
back up my firmware  in zip ..
i get my boot. img  
but  i need to know  how to unblock  bootloader . ever time i try  
device  not found  or time out...  
?i m newbi don't know how  pls help

if you were able to backup firmware using miracle box then you should be able to flash only patched_boot using custom flasher in miracle, see the guide @ https://www.hovatek.com/forum/thread-26213.html --without needing to unlock bootloader

unlocking bootloader might not be possible in your model due to different OEMs using different commands (usually unknown to the general public) OR maybe the bootloader requires key (usually calc by OEM or 3rd party). You need to search online specifically for you device model OR try out commands know to work on other vivo models

you can try this fastboot binaries @ https://drive.google.com/file/d/1-loOC9B...XBsfh/view
try either of this two commands using the fastboot in the link above

• fastboot bbk unlock_vivo
  
• fastboot vivo_bsp unlock_vivo