Mainly putting this here for myself, but if anyone else can be helped, then cool!

GET FACTORY BOOTLOADER AND RADIO (if needed):

  1. get for your device from https://developers.google.com/android/nexus/images
  2. unzip
  3. copy bootloader and radio to a directory
  4. update it using next instructions

UPDATE BOOTLOADER AND RADIO:

# ./adb devices
# ./adb reboot bootloader
# ./fastboot flash bootloader [bootloader file].img
# ./fastboot reboot-bootloader
# ./fastboot flash radio [radio file].img
# ./fastboot reboot-bootloader

DOWNLOAD LATEST ELEMENTALX:

PURENEXUS DOWNLOADS:

HOW TO FLASH PURENEXUS 5X:

  1. Download the latest Pure Nexus zip, latest GApps (recommended ones linked, use others at your own risk), SuperSU (if you want root), and your custom kernel if you have one onto your phone.
  2. Backup any important data.
  3. Boot into TWRP and make a backup (optional but HIGHLY recommended).
  4. Wipe system, data, cache, and dalvik cache in Wipe > Advanced Wipe.
  5. Flash Pure Nexus zip.
  6. Flash GApps zip.
  7. Flash your custom kernel (optional).
  8. Flash SuperSU (optional).
  9. Flash new boot animation.zip (optional)
  10. Reboot and profit.