Fixing a Bootlooping Nexus 5x by Freezing It

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A friend brought me an LG Nexus 5X which wouldn’t power up anymore, after a hard shock (a fall). A symptom being “the Google logo appearing over and over again until it ran out of battery”. Apparently the owner took it to service before, regarding the issue, but “reflashing didn’t work”.

As an owner of a Nexus 5X, I took the matter in my own hands (a.k.a. searching the interwebs - ahem, XDA - for fixes).

What I was dealing with: - Bootloop - nothing more past the Google logo - Wouldn’t stay powered off while charging - plug in, bootloop occurs; not an issue, but makes the charging take longer - Able to access the bootloader menu - useful for powering off, no recovery access available


Searching for clues

Apparently the bootloop is a well known issue on LG phones, but the issue here somehow occurs on Nexus 5Xs and also 6Ps.

The general consensus here with these fixes seem to indicate that the Snapdragon 808/810 chipsets were rushed out by Qualcomm and have degraded to the point where they’re partially broken.

xda-developers

A hardware bricked phone is plausible in this case. Let’s dig deeper - the bootloop fix for the Nexus 6P includes a software fix for the hardware related issue:

This has been achieved by disabling the big cluster of the device’s Snapdragon 810 SoC, which then allows the device to finally reach its lockscreen.

xda-developers

Long story short, you have to flash a custom boot image in order to disable the faulty, big cluster, to make the phone usable again.

These builds have been changed to only use the little cluster of the Snapdragon 810 SoC, effectively disabling the A57 performance cores that are seemingly preventing the device from booting.

xda-developers

Even so, the only way to flash custom images through fastboot (diagnostic protocol from the Android SDK), is with an unlocked phone. Unlocking the Nexus 5X is achieved by ticking the “Enable OEM Unlocking” feature from the Developer Options entry in the Settings app, then running the fastboot flashing unlock command.

The phone is shipped locked, was never unlocked, and now is currently in a bootloop state. How does one access the settings in an unresponsive phone?


Getting the phone to boot

Sources said that leaving the phone in the freezer or heating up the phone could help boot the phone, so I did that. There is probably a security feature (thermal throttler?) which disables the big cluster of the SoC on temperatures that are too low, or too high. I put the phone in the freezer. Wrapped tightly in a zip bag, and next to the frozen peas and spinach.

As weird as it sounds, leaving it get cold for 10 minutes in the freezer allowed me to boot it up and tick the OEM unlocking feature in the Settings. There was no data to be recovered, so the 5% battery it had in was more than enough to get the job done.

Afterwards, I plugged the phone to the laptop, in order to send the fastboot flashing unlock command. The tutorial1 is for phones running Nougat, and I wanted Oreo on this one. As the phone is ready to get flashed, I opened the Android Factory Images page, headed to the “bullhead” for Nexus 5X section, and downloaded the latest image, 8.0.0 (OPR6.170623.023, Nov 2017).

The flashing is done by running the provided shell script flash-all.sh, which contains:

fastboot flash bootloader bootloader-bullhead-bhz21d.img
fastboot reboot-bootloader
sleep 5
fastboot flash radio radio-bullhead-m8994f-2.6.39.3.03.img
fastboot reboot-bootloader
sleep 5
fastboot -w update image-bullhead-opr6.170623.023.zip

This step lasted around 5 minutes. After the latest command, the phone reboots, and obviously, starts to bootloop.

The author of the 5X boot image fix thread released an image for Android Oreo, which I promptly downloaded and applied via fastboot flash boot 4CoreOreo.img. I wanted to have a custom Recovery, too, in case something happens, so I also flashed the TWRP image1, too.

The OP states that the first boot takes a few minutes to boot, up to 20 minutes, so the panic shouldn’t set in too fast, but the phone successfully booted up in less than a minute after the final reboot (subsequent to flashing the boot image & the recovery).

Initial setup done, applications updated, and everything works. Many thanks to XCnathan32, the OP.