Check the status of the bootloader or attempt to unlock/relock it. How to Use the Vivo Fastboot Tool
Power off your Vivo phone. Press and hold the Volume Up + Power buttons simultaneously to enter Fastboot mode.
Link your phone to your PC using a high-quality USB cable.
Ensure you have the latest Vivo USB Drivers and ADB/Fastboot Drivers installed on your PC.
Quickly switch your device from Fastboot mode back to Normal mode or into Recovery.