[Nexus 6P Q&A, Help & Troubleshooting] Gytole:
-"I just saw this and has a similar issue with a phone from a person on craigslist. Bootloader unlocked but SUPPOSEDLY took an OTA update from the nexus images page that was like 3 updates ahead. What i'm guessing happened was there was a bootloader update or sonething weird behind the scenes that was updated along the way but not included in the image ota he flashed. I was able to get his phone out of a bootloop after many failed attempts of erasing and rom flashing in twrp below"-

Back at it again with another Bork Guide..[ PLEASE NOTE, I TAKE NO RESPONSIBILITY FOR BORKED PHONES]

Has anyone tried a manual fastboot erase all and then reflash stock MANUALLY? From Fastboot of course while in the bootloader.

It's (fastboot erase) or fastboot format for some. I forget off the top of my head. If you type the wrong command it will error out asking if you meant to format the partition instead.

fastboot erase recovery

fastboot erase boot

fastboot erase radio (if it will let you, it SOMETIMES does)

fastboot format system

fastboot format userdata

fastboot erase cache (might be format)

fastboot erase vendor (might be format)

Then download the latest factory nexus img, I downloaded just for the sake of this MTC20F.

Extract the FOLDER to your desktop, if you are using 7zip you are gonna have to go into the tar twice because it's weird like that and calls your momma names you don't approve of.

go into the extracted folder and rename bootloader blah blah and radio blah to just bootloader and radio -Make sure it is bootloader.img and radio.img, it should do this automatically but if you have show extensions enabled you can rename them wrong...I think... You'll want them shor cause you're manually flashing them and don't want to type a long name or copy and paste the entire time. Way too much time...

Now, Double click the images-angler-mtc20f, you should see a list of 6 img files and a text.

Now, put that screen in the top right corner or left depending on what's on your desktop, and right click on your desktop and make a new folder, call it whatever you want. I named mine Nexus 6P Manual Flash for obvious test reasons...

Drag and drop the 6 img files from the folder you just side mounted. Then go back a directory to where you renamed bootloader and radio, and copy those two img's into the SAME folder you made.

NOW! Close all windows EXCEPT your Folder with all 8 (EIGHT) IMAGES and this post if you need help flashing and let's get started. And I'm hoping you have fastboot properly installed on your pc/laptop. http://xdaforums.com/showthread.php?t=2317790

BOOT your phone into bootloader mode from an OFF state by PRESSING and HOLDING Volume DOWN then power until it boots to your broken little android.

Now, hold shift and right click IN the folder of all 8 images and click start a command prompt here.

command prompt should start.

Now, plug your phone in, it should "tootle toot", fart or moan whatever sound you you have when a USB peripheral is connected.

Now if you haven't already erase/formatted the phone earlier do so now by scrolling up and either typing the fastboot's manually or copy and paste. "If the command complains did you mean to erase this instead? type in erase instead of format and vice versa. but they should be right.

Now to the flashing. It will return a COMMAND, read for ANY errors and follow this to a T. BOOTLOADER MUST BE FIRST.

I HAVE TRIPLE CHECKED SPELLING YOU CAN COPY AND PASTE THESE ONE BY ONE IN FASTBOOT.

fastboot flash bootloader bootloader.img

fastboot reboot bootloader

fastboot flash radio radio.img

fastboot reboot bootloader

fastboot flash boot boot.img

fastboot flash system system.img

fastboot flash userdata userdata.img

fastboot flash vendor vendor.img

fastboot flash recovery recovery.img

fastboot flash cache cache.img

If all goes well you should have manually reflashed the phone to a complete out of box stock, use the volume rocker to go into recovery and unplug your phone, factory erase the phone then boot it and see if it boots.

I'm interested to see if this works or not...I am not borked, so I will not test it. But sometimes on hard borks this gets me out!