This is mainly for my own records so I don’t have to go searching again, but maybe it will help someone else. This assumes you already have ADB installed and working on your computer, and you have some knowledge of how this all works.

Here’s the steps to update your phone with the latest security updates or bootloader or radio if you’re already running magisk and phh.

  1. Grab the latest Magisk from XDA, get the Uninstaller too and transfer to your phone
  2. Grab the latest PHH SuperUser from XDA and transfer to your phone
  3. Grab the latest ElementalX Kernel and transfer it to your phone
  4. Get the factory image for your device: https://developers.google.com/android/nexus/images
  5. Open the zip and extract boot.img and system.img. If there is a vendor.img, extract that too. Same for bootloader and radio if they are new. You can check the version on the bootloader screen.
  6. Reboot to bootloader, I use Reboot Manager.
  7. On your computer go to the folder where you extracted the images and flash them with the fastboot command:
fastboot flash boot boot.img
fastboot flash system system.img  

And if your device has a vendor.img:

fastboot flash vendor vendor.img

And if your device has a new radio:

fastboot flash radioradio.img

And if there’s a new bootloader:

fastboot flash bootloader bootloader.img
  1. Reboot to recovery (this is very important if your data partition is unencrypted on newer devices)
  2. Flash everything in this order that you copied to the phone earlier
    1. Magisk Uninstaller
    2. Latest Magisk
    3. PHH SuperUser
    4. ElementalX
    5. (optional) custom bootanimation.zip
  3. Wipe dalvik and cache
  4. Reboot and wait a few moments and then you’re in your newly security-patched Android!
  5. You’ll probably want to install Magisk Manager and PHH SuperUser App (not sure if needed?) now.

That’s it!