[Nexus 6P General] billa:
*** I ran into a similar catch-22 issue on my 6P (H1511) the dreaded bootlooping with OEM Unlock turned OFF. ***

*** Couldn't flash the phone because OEM Unlock was off, but couldn't turn OEM Unlock on because it was bootlooping. ***

*** You MUST be able to fix the bootlooping/freezing at least temporarily, in order to turn on OEM Unlock in Developer Options ***

I have tried the "squeezing" method to no avail.

Then tried the heating method, which worked to a point where it has reached the color circles while booting, but then it started looping again.

I figured there's nothing to loose, so I cranked up the heat on the digital heating plate to exactly 140 Celsius for about 10 minutes covered with a paper towel, with only the upper half of the phone's back touching the heating plate (no need to "cook" the lower part with the battery).

It was still looping after the circles appeared, BUT by leaving it to cool off for about an hour, it has finally booted up into the setup page, so I quickly went to Settings > About/Phone/Software Info > clicked the "Build" line 7 times to enable Developer Options, under which I enabled OEM Unlock and ADB Debug.

If it's still bootlooping, you may try to "freezing" method where you would put the phone into the deep freezer for about an hour.

However, heating has worked for me.

Following that, in FastBoot mode I entered the following 3 versions of the flash unlock commands (only one will work out of the 3 which is fine):

fastboot oem unlock

fastboot flashing unlock

fastboot flashing unlock_critical

Downloaded the latest full stock firmware directly from Google.

https://dl.google.com/dl/android/aosp/angler-opm6.171019.030.b1-factory-ab13a98b.zip

Unzip it, and run flash-all.bat

Once the flashing has finished, DO NOT let it boot up, instead hold down the Volume Down as it's about to reboot, which will kick it into bootloader/fastboot mode.

I have tried flashing the Osmosis zip to patch the boot but it didn't work, it was still bootlooping.

So I have flashed a pre-patched 4-Core Boot kernel to fix the bootlooping issue permanently.

For Android 8.1 OPM6.171019.030 flash this 4-Core Boot with the commands below:

https://androidfilehost.com/?fid=13356325061477269711

fastboot flash boot Huawei_H1511_6P_OPM6.171019.030_Boot_4Core.IMG

fastboot reboot-bootloader

At this point flash a 4-Cores patched TWRP, go into TWRP recovery (hold down Volume Down + Power for 10 seconds, Volume Down to "Recovery", Power) and first "format" Data, then "wipe" Cache, Dalvik-Cache, and Data.

Note, all information on your phone will be lost by the above format/wipe operation.

All done, hope this method may help some of you.

And here are some interesting FastBoot commands I've come across....

C:\ADB>fastboot flashing get_unlock_ability

(bootloader) 1

OKAY [ 0.018s]

Finished. Total time: 0.019s

C:\ADB>fastboot getvar all

(bootloader) version:0.01

(bootloader) unlocked:yes

(bootloader) hardware-revision:ANGLER-VN2

(bootloader) version-baseband:angler-03.87

(bootloader) version-bootloader:angler-03.79

(bootloader) display-panel:

(bootloader) charger-screen-enabled:0

(bootloader) max-download-size: 0x1d800000

(bootloader) partition-type:cache:ext4

(bootloader) partition-size:cache: 0x6400000

(bootloader) partition-type:userdata:ext4

(bootloader) partition-size:userdata: 0xdaa17ee00

(bootloader) partition-type:system:ext4

(bootloader) partition-size:system: 0xc0000000

(bootloader) serialno:8XV5T15C11000453

(bootloader) kernel:lk

(bootloader) product:angler

all:

Finished. Total time: 0.172s

Instead of "fastboot getvar all", you can also use "fastboot getvar <variable>" (without the quotes and <>)

Any <variable> from the log above, between "(bootloader)" and the second ":"

For example:

fastboot getvar serialno

Enjoy! :)