This article is my checklist to install the monthly Android security updates into my Nexus 5X.
Since my phone is cursed with the Bootloop of Death (BLOD) hardware problem, I cannot install the vanilla OTA updates. Instead, I have to manually download the official Android image from Google, edit it to apply the fix, and then flash the fixed image into the phone.
About the bootloop: One day, while using my Nexus 5X, it suddenly restarted and became unusable, stuck in an endless boot process (bootloop). Unfortunately, this is a known hardware problem that occurs in both the Nexus 5X and Nexus 6P phones. There is a hacky fix: via software, you should disable two of the six available cores in the phone processor (SoC). Read more about it here, here and here.
Step 1 - Unlock the bootloader
The phone’s bootloader must be unlocked so you can flash the fixed images.
Tutorial: How to unlock the Nexus 5X bootloader
Step 2 - Download the necessary files
Download and unzip the official Android SDK Platform Tools, which contains the required fastboot binary:
Download the Python script used to modify the Android boot images, disabling the faulty hardware:
Download from Google the official, most recent Android image for the Nexus 5X (nicknamed bullhead):
Step 3 - Prepare the files
Unzip the Android image into a new folder. This will be our work folder.
Inside there will be another zip file which contains the boot images. Unzip that too.
# Using Oreo 8.1 files as an example unzip bullhead-opm1.171019.011-factory-3be6fd1c.zip cd bullhead-opm1.171019.011 unzip image-bullhead-opm1.171019.011.zip
Now copy here the downloaded Python script:
cp ~/Downloads/disable_cpu_cores.py .
Also copy here the fastboot binary:
cp ~/Downloads/platform-tools/fastboot .
At this point, all the necessary files are on the same folder:
android-info.txt boot.img bootloader-bullhead-bhz31a.img disable_cpu_cores.py fastboot flash-all.bat flash-all.sh flash-base.sh radio-bullhead-m8994f-2.6.40.4.04.img recovery.img system.img vendor.img
Step 4 - Apply the image fix
Run the Python script on both the boot and recovery images:
python disable_cpu_cores.py boot.img boot_4c.img python disable_cpu_cores.py recovery.img recovery_4c.img
Note that the fixed files have a _4c suffix to make it clear that those are the modified images (limited to 4 cores).
Step 5 - Prepare the phone
Put the phone in Fastboot Mode: turn off the phone and hold Volume Down and Power buttons until the fastboot screen appears.
Tutorial: Nexus 5X: How to Boot into Fastboot Mode
Plug the phone to your computer and make sure it is listed as an available device:
./fastboot devices
If nothing appears, try using another cable. Some cables I tried here were charging-only.
Step 6 - Flash all the images to your phone
Run the official Google script to install the base system images to your phone (bootloader and radio):
PATH="$PWD:$PATH" ./flash-base.sh
The
PATHvariable is necessary so the script can find the./fastbootfile.
Now flash all the other images, making sure your are using the _4c version for the boot and recovery images.
./fastboot flash boot boot_4c.img ./fastboot flash recovery recovery_4c.img ./fastboot flash system system.img ./fastboot flash vendor vendor.img
Now just reboot your phone and enjoy the updated Android!
./fastboot reboot
Troubleshooting: Clear cache partition
Only one time this update process failed on me and I was back stuck on the bootloop. The fix was simple: booting into Recovery Mode and clearing the cache partition.
