Fastboot Stuck with locked bootloader

My problem is much similar to a guy on this post:
http://forum.xda-developers.com/moto...t2634982/page5

I've tried to upgrade my ROM (Retail) from 4.4.4 to 5.1

I had my bootloader unlocked before doing that.

When i did, my phone was unable to finish the update and I got stuck on fastboot. But know it behaves and states that its "Locked". When I try to unlock it, I get that error:

Code:

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c:\motox\adb>fastboot oem unlock XXXXXXXXXX
...
(bootloader) fastboot oem unlock disabled!
FAILED (remote failure)
finished. Total time: 0.278s

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I already tried flashing both the 4.4.4 version I was using, and the version I updated.
I gives me the following error:

Code:

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c:\motox\adb>fastboot flash recovery recovery.img
(bootloader) Variable not supported!
target reported max download size of 805306368 bytes
sending 'recovery' (10240 KB)...
OKAY [ 0.932s]
writing 'recovery'...
(bootloader) Permission denied
FAILED (remote failure)
finished. total time: 1.035s

---

I'm unnable to boot into recovery and anything else, except the fastboot.
Please, help me solving it.