[Moto X General] yeticomes:
I used Motorolas Fastboot on the Mac - here are the commands (1st error was because I forgot to copy the Files to the Folder)

localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/fastboot oem fb_mode_set
< waiting for demacce >
...
OKAY [ 0.253s]
finished. total time: 0.253s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/fastboot oem fb_mode_set
Password:
...
OKAY [ 0.115s]
finished. total time: 0.115s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/mfastboot flash partition gpt.bin
(bootloader) Variable not supported!
target max-download-size: 768MB
error: cannot load 'gpt.bin': No such file or directory

localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/mfastboot flash partition gpt.bin
(bootloader) Variable not supported!
target max-download-size: 768MB
sending 'partition' (32 KB)...
OKAY [ 0.253s]
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
OKAY [ 0.469s]
finished. total time: 0.722s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/mfastboot flash motoboot motoboot.img
(bootloader) Variable not supported!
target max-download-size: 768MB
sending 'motoboot' (1604 KB)...
OKAY [ 0.365s]
writing 'motoboot'...
(bootloader) flashing aboot ...
(bootloader) flashing rpm ...
(bootloader) flashing tz ...
(bootloader) flashing sbl3 ...
(bootloader) flashing sbl2 ...
(bootloader) flashing sbl1 ...
OKAY [ 5.270s]
finished. total time: 5.635s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/mfastboot flash logo logo.bin
(bootloader) Variable not supported!
target max-download-size: 768MB
sending 'logo' (636 KB)...
OKAY [ 0.332s]
writing 'logo'...
OKAY [ 0.900s]
finished. total time: 1.232s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/mfastboot flash boot boot.img
(bootloader) Variable not supported!
target max-download-size: 768MB
sending 'boot' (10240 KB)...
OKAY [ 0.926s]
writing 'boot'...
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 2.116s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/mfastboot flash recovery recovery.img
(bootloader) Variable not supported!
target max-download-size: 768MB
sending 'recovery' (10240 KB)...
OKAY [ 0.945s]
writing 'recovery'...
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 2.145s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/mfastboot flash system system.img
(bootloader) Variable not supported!
target max-download-size: 768MB
Multi-Flash is enabled!
sending 'system' (262144 KB)...
OKAY [ 16.749s]
writing 'system'...
(bootloader) Preflash validation failed
FAILED (remote failure)
finished. total time: 17.719s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/mfastboot flash modem NON-HLOS.bin
(bootloader) Variable not supported!
target max-download-size: 768MB
sending 'modem' (53752 KB)...
OKAY [ 3.683s]
writing 'modem'...
OKAY [ 2.510s]
finished. total time: 6.193s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/fastboot flash erase modemst1
(bootloader) Variable not supported!
error: cannot open 'modemst1'

localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/fastboot erase modemst1
(bootloader) Variable not supported!
erasing 'modemst1'...
OKAY [ 0.455s]
finished. total time: 0.455s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/fastboot erase modemst2
(bootloader) Variable not supported!
erasing 'modemst2'...
OKAY [ 0.461s]
finished. total time: 0.461s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/mfastboot flash fsg fsg.mbn
(bootloader) Variable not supported!
target max-download-size: 768MB
sending 'fsg' (225 KB)...
OKAY [ 0.350s]
writing 'fsg'...
OKAY [ 0.830s]
finished. total time: 1.180s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/fastboot erase cache
(bootloader) Variable not supported!
erasing 'cache'...
OKAY [ 1.347s]
finished. total time: 1.348s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/fastboot erase userdata
(bootloader) Variable not supported!
erasing 'userdata'...
OKAY [ 9.834s]
finished. total time: 9.834s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/fastboot erase customize
(bootloader) Variable not supported!
erasing 'customize'...
OKAY [ 0.228s]
finished. total time: 0.228s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/fastboot erase clogo
(bootloader) Variable not supported!
erasing 'clogo'...
OKAY [ 0.561s]
finished. total time: 0.561s
localhost:platform-tools mac$ sudo /Users/mac/Documents/DEV/sdk/platform-tools/fastboot oem fb_mode_clear
...
OKAY [ 0.174s]
finished. total time: 0.174s
localhost:platform-tools mac$

Do you see anything, why it went wrong? I googled for "(bootloader) Variable not supported!" but was not helpful & the Status was always "finished".

Or do I have to install root?