DragonBoard RB3 - stuck in never ending boot loop

I am trying to get my DragonBoard 845c (RB3) dev kit up and running with AOSP mainline following Using Reference Boards  |  Android Open Source Project by performing these steps:

  1. Download the Android source tree:
    repo init -u platform/manifest - Git at Google -b master
    repo sync -j8
  2. Build:
    . ./build/envsetup.sh
    lunch db845c-userdebug
    make -j24
  3. download kernel source
    repo init -u kernel/manifest - Git at Google -b common-android-mainline
    repo sync -j8 -c
  4. Build kernel
    BUILD_CONFIG=common/build.config.db845c ./build/build.sh
  5. copy all kernel artifacts to platform/device/linaro/dragonboard-kernel/android-mainline
  6. rebuild user space
    make TARGET_KERNEL_USE=mainline -j24
  7. flash local images from AOSP build
  8. download and extract latest aosp bootloader dragonboard-845c-bootloader-ufs-aosp-90.zip - cd to dragonboard-845c-bootloader-ufs-aosp-90 and run ./flash_all
  9. reboot - fastboot reboot - to ensure correct bootloader
  10. cd platform/device/linaro/dragonboard/installer/db845c then run ./flash-all-aosp.sh
    which runs successfully to completion.
  11. reboot device and gets stuck in boot loop

how can I upload my boot logs?

Use a online tool like https://pastebin.com and copy link here