Failed -remote 39-flashing Lock Flag Is Locked. Please Unlock It First 39-- Link

After your device reboots from the standard unlock, boot it back into fastboot mode and run fastboot flashing unlock_critical . Confirm the unlock on your device.

Tap the row 7 consecutive times until a toast notification reads, "You are now a developer!" After your device reboots from the standard unlock,

On older devices (typically pre-2015), you might need to use the legacy command fastboot oem unlock instead [12†L22][12†L33]. This command also initiates the unlock process and will wipe your data. This command also initiates the unlock process and

Type fastboot devices and verify your device's serial number appears. After your device reboots from the standard unlock,

Finally, type fastboot reboot to restart your device. Congratulations, you have successfully unlocked your bootloader!

In essence, the device is saying: "I see you want to flash something, but my security says no. Go through the official unlocking process first."