[Nexus 6 Q&A, Help & Troubleshooting] NeCr0mStR:
Already set to OEM unlocked because it was unlocked before, did the flash again and get this:

(bootloader) has-slot:bootloader: not found

target reported max download size of 536870912 bytes

sending 'bootloader' (4071 KB)...

OKAY [ 0.145s]

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 [ 0.471s]

finished. total time: 0.616s

rebooting into bootloader...

OKAY [ 0.000s]

finished. total time: 0.151s

(bootloader) has-slot:radio: not found

target reported max download size of 536870912 bytes

sending 'radio' (115507 KB)...

OKAY [ 4.207s]

writing 'radio'...

(bootloader) flashing modem ...

(bootloader) flashing mdm1m9kefs1 ...

(bootloader) flashing mdm1m9kefs2 ...

(bootloader) flashing mdm1m9kefs3 ...

(bootloader) flashing versions ...

OKAY [ 1.534s]

finished. total time: 5.741s

rebooting into bootloader...

OKAY [ 0.000s]

finished. total time: 0.151s

target reported max download size of 536870912 bytes

(bootloader) has-slot:boot: not found

archive does not contain 'boot.sig'

(bootloader) has-slot:recovery: not found

archive does not contain 'recovery.sig'

(bootloader) has-slot:system: not found

archive does not contain 'system.sig'

archive does not contain 'vendor.img'

wiping userdata...

Creating filesystem with parameters:

Size: 28474998784

Block size: 4096

Blocks per group: 32768

Inodes per group: 8160

Inode size: 256

Journal blocks: 32768

Label:

Blocks: 6951904

Block groups: 213

Reserved block group size: 1024

Created filesystem with 11/1738080 inodes and 153124/6951904 blocks

wiping cache...

Creating filesystem with parameters:

Size: 268435456

Block size: 4096

Blocks per group: 32768

Inodes per group: 8192

Inode size: 256

Journal blocks: 1024

Label:

Blocks: 65536

Block groups: 2

Reserved block group size: 15

Created filesystem with 11/16384 inodes and 2089/65536 blocks

--------------------------------------------

Bootloader Version...: moto-apq8084-71.21

Baseband Version.....: D4.01-9625-05.42+FSG-9625-02.113

Serial Number........: ZX1G22Q3ZV

--------------------------------------------

checking product...

OKAY [ 0.002s]

checking version-bootloader...

OKAY [ 0.002s]

checking version-baseband...

OKAY [ 0.003s]

sending 'boot' (8535 KB)...

OKAY [ 0.304s]

writing 'boot'...

OKAY [ 0.140s]

sending 'recovery' (13921 KB)...

OKAY [ 0.479s]

writing 'recovery'...

OKAY [ 0.191s]

sending sparse 'system' 1/3 (508909 KB)...

OKAY [ 19.620s]

writing 'system' 1/3...

OKAY [ 7.191s]

sending sparse 'system' 2/3 (524036 KB)...

OKAY [ 19.858s]

writing 'system' 2/3...

OKAY [ 7.148s]

sending sparse 'system' 3/3 (443892 KB)...

OKAY [ 17.295s]

writing 'system' 3/3...

OKAY [ 5.945s]

erasing 'userdata'...

OKAY [ 1.557s]

sending 'userdata' (139061 KB)...

OKAY [ 4.977s]

writing 'userdata'...

OKAY [ 2.552s]

erasing 'cache'...

OKAY [ 0.037s]

sending 'cache' (6248 KB)...

OKAY [ 0.229s]

writing 'cache'...

OKAY [ 0.115s]

rebooting...

finished. total time: 87.805s

You can see that several thins show that they can't be flashed. I have never seen this before and there is nothing I can find with the Googles.