[G 2014 Q&A, Help & Troubleshooting] kesy85:
yes to both the questions.

I've tried also using easy installer but it's simply a .bat file containing the same commands I manually use.

And i've got this errors while flashing stock firmware:

mfastboot flash partition gpt.bin
target max-sparse-size: 256MB
sending 'partition' (32 KB)...
OKAY [ 0.027s]
writing 'partition'...
OKAY [ 0.324s]
finished. total time: 0.351s

mfastboot flash motoboot motoboot.img
target max-sparse-size: 256MB
sending 'motoboot' (2184 KB)...
OKAY [ 0.101s]
writing 'motoboot'...
(bootloader) flashing tz ...
(bootloader) flashing rpm ...
(bootloader) Failed to erase partition
(bootloader) Failed to flash rpm
FAILED (remote failure)
finished. total time: 100.186s

mfastboot flash logo logo.bin
target max-sparse-size: 256MB
sending 'logo' (697 KB)...
OKAY [ 5.028s]
writing 'logo'...
(bootloader) Failed to erase partition
(bootloader) Failed to flash partition logo
FAILED (remote failure)
finished. total time: 19.988s

mfastboot flash boot boot.img
target max-sparse-size: 256MB
sending 'boot' (10200 KB)...
OKAY [ 5.325s]
writing 'boot'...
(bootloader) Failed to erase partition
(bootloader) Failed to flash partition boot
FAILED (remote failure)
finished. total time: 10.344s

mfastboot flash recovery recovery.img
target max-sparse-size: 256MB
sending 'recovery' (10280 KB)...
OKAY [ 5.334s]
writing 'recovery'...
(bootloader) Failed to erase partition
(bootloader) Failed to flash partition recovery
FAILED (remote failure)
finished. total time: 10.358s

mfastboot flash system system.img_sparsechunk.0
target max-sparse-size: 256MB
sending 'system' (257619 KB)...
OKAY [ 13.069s]
writing 'system'...
(bootloader) Failed to erase partition
FAILED (remote failure)
finished. total time: 18.137s

mfastboot flash system system.img_sparsechunk.1
target max-sparse-size: 256MB
sending 'system' (256618 KB)...
OKAY [ 13.045s]
writing 'system'...
(bootloader) Failed to flash sparse image
FAILED (remote failure)
finished. total time: 18.140s

mfastboot flash system system.img_sparsechunk.2
target max-sparse-size: 256MB
sending 'system' (260464 KB)...
^[[AOKAY [ 13.159s]
writing 'system'...
^[[A(bootloader) Failed to flash sparse image
FAILED (remote failure)
finished. total time: 18.237s

mfastboot flash system system.img_sparsechunk.2
target max-sparse-size: 256MB
sending 'system' (260464 KB)...
OKAY [ 13.164s]
writing 'system'...
(bootloader) Failed to validate sparse image
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 13.246s

mfastboot flash system system.img_sparsechunk.3
target max-sparse-size: 256MB
sending 'system' (244081 KB)...
OKAY [ 12.647s]
writing 'system'...
(bootloader) Failed to flash sparse image
FAILED (remote failure)
finished. total time: 17.689s

mfastboot flash system system.img_sparsechunk.4
target max-sparse-size: 256MB
sending 'system' (36088 KB)...
OKAY [ 6.149s]
writing 'system'...
(bootloader) Failed to flash sparse image
FAILED (remote failure)
finished. total time: 11.178s

mfastboot flash modem NON-HLOS.bin
target max-sparse-size: 256MB
sending 'modem' (49356 KB)...
OKAY [ 6.558s]
writing 'modem'...
(bootloader) Failed to erase partition
(bootloader) Failed to flash partition modem
FAILED (remote failure)
finished. total time: 11.584s

mfastboot erase modemst1
erasing 'modemst1'...
(bootloader) Failed to erase partition
FAILED (remote failure)
finished. total time: 9.987s

mfastboot erase modemst2
erasing 'modemst2'...
(bootloader) Failed to erase partition
FAILED (remote failure)
finished. total time: 9.992s

mfastboot erase cache
erasing 'cache'...
(bootloader) Failed to erase partition
FAILED (remote failure)
finished. total time: 9.986s

mfastboot erase userdata
erasing 'userdata'...
(bootloader) Failed to erase partition
FAILED (remote failure)
finished. total time: 9.986s