[Moto G Q&A, Help & Troubleshooting] tuxboson:
hallo, puh, installed all the stuff ... but the errors during installation of stok are the same.

c:\01\org>mfastboot flash partition gpt.bin
target max-sparse-size: 256MB
sending 'partition' (32 KB)...
OKAY [ 0.078s]
writing 'partition'...
(bootloader) This may take a few seconds, if a
(bootloader) different partition table is being
(bootloader) flashed since we need to backup
(bootloader) and restore a few partitions
(bootloader) Flashing primary GPT image...
(bootloader) Flashing backup GPT image...
OKAY [ 0.390s]
finished. total time: 0.484s

c:\01\org>mfastboot flash motoboot motoboot.img
target max-sparse-size: 256MB
sending 'motoboot' (1953 KB)...
OKAY [ 0.109s]
writing 'motoboot'...
(bootloader) flashing tz ...
(bootloader) flashing rpm ...
(bootloader) flashing sdi ...
(bootloader) flashing aboot ...
(bootloader) flashing sbl1 ...
OKAY [ 1.342s]
finished. total time: 1.451s

c:\01\org>mfastboot flash logo logo.bin
target max-sparse-size: 256MB
sending 'logo' (1060 KB)...
OKAY [ 0.094s]
writing 'logo'...
OKAY [ 0.156s]
finished. total time: 0.265s

c:\01\org>mfastboot flash boot boot.img
target max-sparse-size: 256MB
sending 'boot' (10240 KB)...
OKAY [ 0.390s]
writing 'boot'...
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 0.437s

c:\01\org>mfastboot flash recovery recovery.img
target max-sparse-size: 256MB
sending 'recovery' (10240 KB)...
OKAY [ 0.390s]
writing 'recovery'...
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 0.452s

c:\01\org>mfastboot flash system system.img_sparsechunk.
target max-sparse-size: 256MB
sending 'system' (254357 KB)...
OKAY [ 8.221s]
writing 'system'...
(bootloader) Invalid signed image
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 8.393s

c:\01\org>mfastboot flash system system.img_sparsechunk.
target max-sparse-size: 256MB
sending 'system' (261416 KB)...
OKAY [ 8.471s]
writing 'system'...
(bootloader) Invalid signed image
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 8.533s

c:\01\org>mfastboot flash system system.img_sparsechunk.
target max-sparse-size: 256MB
sending 'system' (250179 KB)...
OKAY [ 8.081s]
writing 'system'...
(bootloader) Invalid signed image
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 8.143s

c:\01\org>mfastboot flash system system.img_sparsechunk.
target max-sparse-size: 256MB
error: cannot load 'system.img_sparsechunk.3': No error

c:\01\org>mfastboot flash modem NON-HLOS.bin
target max-sparse-size: 256MB
sending 'modem' (59132 KB)...
OKAY [ 1.950s]
writing 'modem'...
OKAY [ 2.995s]
finished. total time: 4.961s

c:\01\org>mfastboot erase modemst1
erasing 'modemst1'...
OKAY [ 0.031s]
finished. total time: 0.031s

c:\01\org>mfastboot erase modemst2
erasing 'modemst2'...
OKAY [ 0.031s]
finished. total time: 0.031s

c:\01\org>mfastboot flash fsg fsg.mbn
target max-sparse-size: 256MB
sending 'fsg' (661 KB)...
OKAY [ 0.094s]
writing 'fsg'...
OKAY [ 5.335s]
finished. total time: 5.429s

c:\01\org>mfastboot erase cache
erasing 'cache'...
OKAY [ 0.094s]
finished. total time: 0.109s

c:\01\org>mfastboot erase userdata
erasing 'userdata'...
OKAY [ 0.234s]
finished. total time: 0.234s

Device still starting with

failed to validate system image

Fastboot Reason: fall-through from normal boot mode