If your phone won’t boot past the logo:
This guide is for educational purposes only. Unlocking the bootloader voids your warranty, wipes all user data, and may brick your device if done incorrectly. Vivo does not officially support bootloader unlocking for this model. Proceed at your own risk. unlock bootloader vivo y71 high quality
that has secure boot disabled
This method works because Vivo (formerly BBK Electronics) left some engineering commands accessible in the bootloader of their older devices. For the Y71, success depends heavily on your current firmware version. Older Android 8.1 firmware has a higher success rate than newer versions. If your phone won’t boot past the logo:
cd C:\adb fastboot devices
Do you have the Y71, Y71i, or Y71t model, or are you unsure which method to try? Let me know in the comments, and I will do my best to help guide you further. Proceed at your own risk
Re-enable using the method described in Step 1.