6.0 marshmallow - Cannot flash Moto X Style - Due to "Pre-flash validation failed" error

I have bricked my device (The Motorola Moto X Style (UK)) after trying to install SuperSU on my device running the latest MM build.

Through hours and hours of research, I am trying to flash a stock build to my device, downloaded from this website https://firmware.center/firmware/Motorola/Moto%20X%20Style/Stock/XT1572/

I am following the instructions in this thread: https://forum.xda-developers.com/moto-x-style/development/firmware-moto-x-style-pure-stock-t3272486

These are the commands you are told to enter into command prompt:

fastboot oem lock begin
fastboot flash partition gpt.bin
fastboot flash bootloader bootloader.img
fastboot flash logo logo.bin
fastboot flash boot boot.img
fastboot flash recovery recovery.img
fastboot flash system system.img_sparsechunk.0
fastboot flash system system.img_sparsechunk.1
fastboot flash system system.img_sparsechunk.2
fastboot flash system system.img_sparsechunk.3

fastboot flash system system.img_sparsechunk.4
fastboot flash system system.img_sparsechunk.5
fastboot flash system system.img_sparsechunk.6
fastboot flash system system.img_sparsechunk.7
fastboot flash system system.img_sparsechunk.8
fastboot flash system system.img_sparsechunk.9
fastboot flash modem NON-HLOS.bin
fastboot erase modemst1 
fastboot erase modemst2 
fastboot flash fsg fsg.mbn

fastboot erase cache 
fastboot erase userdata
fastboot oem lock
fastboot reboot

I have tried 2 different builds, both of them failing when reaching the same commands. This is my console window at the moment after reaching the sparsechunk.2 file

    D:\platform-tools-latest-windows\platform-tools>fastboot devices
TA391006KH      fastboot

D:\platform-tools-latest-windows\platform-tools>fastboot flash partition D:\XT1572_CLARK_RETEU_6.0.1_MPHS24.107-58-5_cid7_subsidy-DEFAULT_CFC.xml\gpt.bin

(bootloader) slot-count: not found
(bootloader) slot-suffixes: not found
(bootloader) slot-suffixes: not found
(bootloader) has-slot:partition: not found
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: 0.393s

D:\platform-tools-latest-windows\platform-tools>fastboot flash bootloader D:\XT1572_CLARK_RETEU_6.0.1_MPHS24.107-58-5_cid7_subsidy-DEFAULT_CFC.xml\bootloader.img
(bootloader) slot-count: not found
(bootloader) slot-suffixes: not found
(bootloader) slot-suffixes: not found
(bootloader) has-slot:bootloader: not found
target reported max download size of 536870912 bytes
sending 'bootloader' (2699 KB)...
OKAY [  0.155s]

writing 'bootloader'...
(bootloader) flashing aboot ...
(bootloader) flashing sbl1 ...
(bootloader) flashing pmic ...
(bootloader) flashing rpm ...
(bootloader) flashing tz ...
(bootloader) flashing hyp ...
(bootloader) flashing sdi ...
OKAY [  1.637s]
finished. total time: 1.805s


D:\platform-tools-latest-windows\platform-tools>fastboot flash logo D:\XT1572_CLARK_RETEU_6.0.1_MPHS24.107-58-5_cid7_subsidy-DEFAULT_CFC.xml\logo.bin
(bootloader) slot-count: not found
(bootloader) slot-suffixes: not found
(bootloader) slot-suffixes: not found
(bootloader) has-slot:logo: not found
target reported max download size of 536870912 bytes
sending 'logo' (3687 KB)...
OKAY [  0.081s]
writing 'logo'...

OKAY [  0.116s]
finished. total time: 0.204s

D:\platform-tools-latest-windows\platform-tools>fastboot flash boot D:\XT1572_CLARK_RETEU_6.0.1_MPHS24.107-58-5_cid7_subsidy-DEFAULT_CFC.xml\boot.img
(bootloader) slot-count: not found
(bootloader) slot-suffixes: not found
(bootloader) slot-suffixes: not found
(bootloader) has-slot:boot: not found
target reported max download size of 536870912 bytes
sending 'boot' (40960 KB)...

OKAY [  0.985s]
writing 'boot'...
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 1.702s

D:\platform-tools-latest-windows\platform-tools>fastboot flash recovery D:\XT1572_CLARK_RETEU_6.0.1_MPHS24.107-58-5_cid7_subsidy-DEFAULT_CFC.xml\recovery.img
(bootloader) slot-count: not found
(bootloader) slot-suffixes: not found
(bootloader) slot-suffixes: not found

(bootloader) has-slot:recovery: not found
target reported max download size of 536870912 bytes
sending 'recovery' (41040 KB)...
OKAY [  0.961s]
writing 'recovery'...
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 1.728s

D:\platform-tools-latest-windows\platform-tools>fastboot flash system D:\XT1572_CLARK_RETEU_6.0.1_MPHS24.107-58-5_cid7_subsidy-DEFAULT_CFC.xml\system.img_sparsechunk.0

(bootloader) slot-count: not found
(bootloader) slot-suffixes: not found
(bootloader) slot-suffixes: not found
(bootloader) has-slot:system: not found
target reported max download size of 536870912 bytes
sending 'system' (257199 KB)...
OKAY [  5.813s]
writing 'system'...
(bootloader) Invalid signed image
(bootloader) Preflash validation failed

FAILED (remote failure)
finished. total time: 6.232s

D:\platform-tools-latest-windows\platform-tools>fastboot flash system D:\XT1572_CLARK_RETEU_6.0.1_MPHS24.107-58-5_cid7_subsidy-DEFAULT_CFC.xml\system.img_sparsechunk.1
(bootloader) slot-count: not found
(bootloader) slot-suffixes: not found
(bootloader) slot-suffixes: not found
(bootloader) has-slot:system: not found
target reported max download size of 536870912 bytes
sending 'system' (255632 KB)...

OKAY [  5.848s]
writing 'system'...
(bootloader) Invalid signed image
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 5.917s

D:\platform-tools-latest-windows\platform-tools>fastboot flash system D:\XT1572_CLARK_RETEU_6.0.1_MPHS24.107-58-5_cid7_subsidy-DEFAULT_CFC.xml\system.img_sparsechunk.2
(bootloader) slot-count: not found
(bootloader) slot-suffixes: not found

(bootloader) slot-suffixes: not found
(bootloader) has-slot:system: not found
target reported max download size of 536870912 bytes
sending 'system' (255866 KB)...
OKAY [  5.851s]
writing 'system'...
(bootloader) Invalid signed image
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 5.920s

What am I doing wrong? Do these errors mean that I am trying to flash the wrong firmware?

Thanks for any help in advance!