Flash Soft Bricked Locked Nexus 6P How can I get my soft bricked Nexus 6P working again? 

I don't mind flashing it, losing all data etc. I'd rather have it done now than send it away to be fixed. 

It's caught in a boot loop where it only makes it to the white Google logo, then restarts. I can get to the bootloader and occasionally I can get to stock recovery mode. 

Running adb oem device-info returns:

(bootloader)    Device tampered: false
(bootloader)    Device unlocked: false
(bootloader)    Charger screen enabled: false
(bootloader)    Display panel:
OKAY [  0.058s]
finished. total time: 0.058s


Running fastboot flashing unlock returns:

...
FAILED (remote: oem unlock is not allowed)
finished. total time: 0.021s


What is my next step here? Any help is appreciated.
I think your bootloader is locked you need to get the unlock key from the manufacturer website i have done it on sony phones to look at an example visit the sony developer site and read as much as you can to understand better what is going on