Please tell us some basic information before asking for help:
Firmware Version: qkq1.ww_phone-17.2017.2004.424.20200414
Rooted or not:not
Frequency of Occurrence:not able to use fastboot mode for unlock boot loader
APP Name & APP Version (If your issue relates to the app):
In addition to information above, please also provide as much details as you can, e.g., using scenario, what troubleshooting you've already done, screenshot, etc.