[X Style (Pure) Q&A, Help & Troubleshooting] Belotto:
I really wasn´t successful...

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> adb reboot-bootloader

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> fastboot flash partition gpt.bin

target reported max download size of 536870912 bytes

sending 'partition' (32 KB)...

OKAY [ 0.016s]

writing 'partition'...

(

bootloader) Preflash validation failed

FAILED (remote failure)

finished. total time: 0.370s

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> fastboot flash motoboot motoboot.img

error: cannot load 'motoboot.img'

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> fastboot reboot-bootloader

rebooting into bootloader...

OKAY [ 0.000s]

finished. total time: 0.000s

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> fastboot flash logo logo.bin

target reported max download size of 536870912 bytes

sending 'logo' (3687 KB)...

OKAY [ 0.137s]

writing 'logo'...

OKAY [ 0.200s]

finished. total time: 0.337s

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> fastboot flash boot boot.img

target reported max download size of 536870912 bytes

sending 'boot' (40960 KB)...

OKAY [ 1.518s]

writing 'boot'...

(bootloader) Preflash validation failed

FAILED (remote failure)

finished. total time: 1.888s

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> fastboot flash recovery recovery.img

target reported max download size of 536870912 bytes

sending 'recovery' (41040 KB)...

OKAY [ 1.534s]

writing 'recovery'...

(bootloader) Preflash validation failed

FAILED (remote failure)

finished. total time: 1.887s

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> fastboot flash system system.img

target reported max download size of 536870912 bytes

sending sparse 'system' (509631 KB)...

OKAY [ 17.857s]

writing 'system'...

(bootloader) Invalid signed image

(bootloader) Preflash validation failed

FAILED (remote failure)

finished. total time: 18.357s

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> fastboot reboot

rebooting...

finished. total time: 0.016s

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> fastboot erase userdata

erasing 'userdata'...

OKAY [ 6.423s]

finished. total time: 6.423s

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> fastboot erase cache

erasing 'cache'...

OKAY [ 0.031s]

finished. total time: 0.031s

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> fastboot oem lock

...

(bootloader) Please run fastboot oem lock begin first!

OKAY [ 0.015s]

finished. total time: 0.015s

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> fastboot oem lock begin

...

(bootloader) Not supported command in current status!

FAILED (remote failure)

finished. total time: 0.017s

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US> fastboot oem lock

...

(bootloader) Please run fastboot oem lock begin first!

OKAY [ 0.000s]

finished. total time: 0.000s

PS C:\Android\sdk\platform-tools\CLARK_RETUS_MPH24.49-18_18_retus_US>