nexus6 bootloader上锁报错 FAILED (remote: 'unknown command')

报错内容：

E:\迅雷下载>fastboot oem lock
FAILED (remote: 'unknown command')

解决方法：

1.首先打开开发者模式启动usb调试

2.重启到fastboot ，输入

E:\迅雷下载>fastboot flashing lock
(bootloader) Please select 'YES' on screen if you want to continue...

此时会在手机屏幕看见一个提示，选yes按电源键确定
(bootloader) Locking bootloader...
(bootloader) Locked!
OKAY [ 19.432s]
Finished. Total time: 19.438s