[Nexus 6 Q&A, Help & Troubleshooting] nitrous²:
Still getting the same error message. Here's the full CMD log if you think I might have missed something. The only posts I could finde on the internet where the line "please run fastboot oem lock begin first" command is wirtten are related to the Moto X and some other Motorola devices. Have any of you guys had your bootloader successfully (re-)locked?

BTW; It doesn't matter whether I use mfastboot or normal fastboot since both give me the same error messages. Both saying "(...) missing system.img" and/or "(...) sst lock failure". I just read that using mfastboot the error "(...) missing system.img" upon flashing a factory image via flash-all.bat would be solved.

Microsoft Windows [Version 6.3.9600]

(c) 2013 Microsoft Corporation. Alle Rechte vorbehalten.

C:\Users\xxxxx>M:

M:\>cd M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>mfastboot erase bo

ot

erasing 'boot'...

(bootloader) Erase allowed in unlocked state

OKAY [ 0.030s]

finished. total time: 0.031s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>mfastboot erase re

covery

erasing 'recovery'...

(bootloader) Erase allowed in unlocked state

OKAY [ 0.019s]

finished. total time: 0.020s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>mfastboot erase sy

stem

erasing 'system'...

(bootloader) Erase allowed in unlocked state

OKAY [ 1.138s]

finished. total time: 1.139s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>mfastboot erase us

erdata

erasing 'userdata'...

OKAY [ 19.200s]

finished. total time: 19.203s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>mfastboot erase ca

che

erasing 'cache'...

OKAY [ 0.054s]

finished. total time: 0.057s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>mfastboot flash bo

otloader bootloader-shamu-moto-apq8084-71.10.img

target max-sparse-size: 256MB

sending 'bootloader' (3807 KB)...

OKAY [ 0.126s]

writing 'bootloader'...

(bootloader) flashing 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...

(bootloader) flashing aboot ...

(bootloader) flashing sbl1 ...

(bootloader) flashing rpm ...

(bootloader) flashing tz ...

(bootloader) flashing sdi ...

(bootloader) flashing logo ...

OKAY [ 0.293s]

finished. total time: 0.423s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>mfastboot reboot-b

ootloader

rebooting into bootloader...

OKAY [ 0.003s]

finished. total time: 0.004s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>mfastboot flash ra

dio radio-shamu-d4.0-9625-02.101.img

target max-sparse-size: 256MB

sending 'radio' (85419 KB)...

OKAY [ 2.743s]

writing 'radio'...

(bootloader) flashing modem ...

(bootloader) flashing mdm1m9kefs1 ...

(bootloader) flashing mdm1m9kefs2 ...

(bootloader) flashing mdm1m9kefs3 ...

(bootloader) flashing versions ...

OKAY [ 1.231s]

finished. total time: 3.977s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>mfastboot reboot-b

ootloader

rebooting into bootloader...

OKAY [ 0.003s]

finished. total time: 0.003s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>mfastboot flash bo

ot boot.img

target max-sparse-size: 256MB

sending 'boot' (7731 KB)...

OKAY [ 0.254s]

writing 'boot'...

OKAY [ 0.211s]

finished. total time: 0.470s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>mfastboot flash re

covery recovery.img

target max-sparse-size: 256MB

sending 'recovery' (8321 KB)...

OKAY [ 0.275s]

writing 'recovery'...

OKAY [ 0.115s]

finished. total time: 0.394s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>mfastboot flash sy

stem system.img

target max-sparse-size: 256MB

Sparse-Flash is enabled!

sending sparse 'system' (259609 KB)...

OKAY [ 9.039s]

writing 'system'...

OKAY [ 3.280s]

sending sparse 'system' (262074 KB)...

OKAY [ 9.176s]

writing 'system'...

OKAY [ 3.457s]

sending sparse 'system' (258556 KB)...

OKAY [ 9.355s]

writing 'system'...

OKAY [ 3.674s]

sending sparse 'system' (252069 KB)...

OKAY [ 8.969s]

writing 'system'...

OKAY [ 3.227s]

sending sparse 'system' (257573 KB)...

OKAY [ 9.353s]

writing 'system'...

OKAY [ 4.308s]

sending sparse 'system' (258051 KB)...

OKAY [ 9.256s]

writing 'system'...

OKAY [ 3.577s]

sending sparse 'system' (189345 KB)...

OKAY [ 6.716s]

writing 'system'...

OKAY [ 2.393s]

finished. total time: 85.806s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>fastboot flash cac

he cache.img

target reported max download size of 536870912 bytes

erasing 'cache'...

OKAY [ 0.015s]

sending 'cache' (6248 KB)...

OKAY [ 0.209s]

writing 'cache'...

OKAY [ 0.100s]

finished. total time: 0.331s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>fastboot flash use

rdata userdata.img

target reported max download size of 536870912 bytes

erasing 'userdata'...

OKAY [ 0.184s]

sending 'userdata' (138868 KB)...

OKAY [ 4.463s]

writing 'userdata'...

OKAY [ 1.983s]

finished. total time: 6.639s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>fastboot oem lock

...

(bootloader) FAIL: Please run fastboot oem lock begin first!

(bootloader) sst lock failure!

FAILED (remote failure)

finished. total time: 0.012s

M:\SHAMU\FACTORY IMAGE\LMY47z\shamu-lmy47z\image-shamu-lmy47z>