[Moto G Q&A, Help & Troubleshooting] adhinos:
D:\MOTO G\51>mfastboot.exe flash partition gpt.bin
target max-sparse-size: 256MB
sending 'partition' (32 KB)...
OKAY [ 0.029s]
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 [ 0.304s]
finished. total time: 0.336s

D:\MOTO G\51>mfastboot.exe flash motoboot motoboot.img
target max-sparse-size: 256MB
sending 'motoboot' (1953 KB)...
OKAY [ 0.093s]
writing 'motoboot'...
(bootloader) flashing tz ...
(bootloader) flashing rpm ...
(bootloader) flashing sdi ...
(bootloader) flashing aboot ...
(bootloader) flashing sbl1 ...
OKAY [ 1.110s]
finished. total time: 1.209s

D:\MOTO G\51>mfastboot.exe reboot-bootloader
rebooting into bootloader...
OKAY [ 0.003s]
finished. total time: 0.004s

D:\MOTO G\51>pause
Press any key to continue . . .

D:\MOTO G\51>mfastboot.exe flash partition gpt.bin
target max-sparse-size: 256MB
sending 'partition' (32 KB)...
OKAY [ 0.029s]
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 [ 0.308s]
finished. total time: 0.344s

D:\MOTO G\51>mfastboot.exe flash motoboot motoboot.img
target max-sparse-size: 256MB
sending 'motoboot' (1953 KB)...
OKAY [ 0.099s]
writing 'motoboot'...
(bootloader) flashing tz ...
(bootloader) flashing rpm ...
(bootloader) flashing sdi ...
(bootloader) flashing aboot ...
(bootloader) flashing sbl1 ...
OKAY [ 1.095s]
finished. total time: 1.199s

D:\MOTO G\51>mfastboot.exe flash logo logo.bin
target max-sparse-size: 256MB
sending 'logo' (1060 KB)...
OKAY [ 0.073s]
writing 'logo'...
OKAY [ 0.133s]
finished. total time: 0.213s

D:\MOTO G\51>mfastboot.exe flash boot boot.img
target max-sparse-size: 256MB
sending 'boot' (10240 KB)...
OKAY [ 0.363s]
writing 'boot'...
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 0.430s

D:\MOTO G\51>mfastboot.exe flash recovery recovery.img
target max-sparse-size: 256MB
sending 'recovery' (10240 KB)...
OKAY [ 0.371s]
writing 'recovery'...
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 0.406s

D:\MOTO G\51>mfastboot.exe flash system system.img_sparsechunk.0
target max-sparse-size: 256MB
sending 'system' (257755 KB)...
OKAY [ 8.108s]
writing 'system'...
(bootloader) Invalid signed image
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 8.244s

D:\MOTO G\51>mfastboot.exe flash system system.img_sparsechunk.1
target max-sparse-size: 256MB
sending 'system' (256953 KB)...
OKAY [ 8.084s]
writing 'system'...
(bootloader) Invalid signed image
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 8.159s

D:\MOTO G\51>mfastboot.exe flash system system.img_sparsechunk.2
target max-sparse-size: 256MB
sending 'system' (260396 KB)...
OKAY [ 8.192s]
writing 'system'...
(bootloader) Invalid signed image
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 8.269s

D:\MOTO G\51>mfastboot.exe flash system system.img_sparsechunk.3
target max-sparse-size: 256MB
sending 'system' (166572 KB)...
OKAY [ 5.260s]
writing 'system'...
(bootloader) Invalid signed image
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 5.325s

D:\MOTO G\51>mfastboot.exe flash modem NON-HLOS.bin
target max-sparse-size: 256MB
sending 'modem' (49376 KB)...
OKAY [ 1.599s]
writing 'modem'...
OKAY [ 2.422s]
finished. total time: 4.026s

D:\MOTO G\51>mfastboot.exe erase modemst1
erasing 'modemst1'...
OKAY [ 0.025s]
finished. total time: 0.026s

D:\MOTO G\51>mfastboot.exe erase modemst2
erasing 'modemst2'...
OKAY [ 0.058s]
finished. total time: 0.060s

D:\MOTO G\51>mfastboot.exe flash fsg fsg.mbn
target max-sparse-size: 256MB
sending 'fsg' (103 KB)...
OKAY [ 0.100s]
writing 'fsg'...
OKAY [ 5.300s]
finished. total time: 5.407s

D:\MOTO G\51>mfastboot.exe erase cache
erasing 'cache'...
OKAY [ 0.085s]
finished. total time: 0.088s

D:\MOTO G\51>mfastboot.exe erase userdata
erasing 'userdata'...
OKAY [ 0.492s]
finished. total time: 0.495s

D:\MOTO G\51>mfastboot.exe oem fb_mode_clear
...
OKAY [ 0.002s]
finished. total time: 0.003s

D:\MOTO G\51>mfastboot.exe reboot-bootloader
rebooting into bootloader...
OKAY [ 0.022s]
finished. total time: 0.024s

I have tried all the rom . the result is the same . What is wrong ??