C:\Users\Alejandro\AppData\Local\Android\android-sdk\platform-tools>adb devices
List of devices attached
ZX1G423BMR device
C:\Users\Alejandro\AppData\Local\Android\android-sdk\platform-tools>adb reboot b
ootloader
C:\Users\Alejandro\AppData\Local\Android\android-sdk\platform-tools>fastboot oem
lock
...
(bootloader) Please flash valid signed images firstly!
FAILED (remote failure)
finished. total time: 0.070s
