Some debug tips before you start

Add another boot config

We highly recommend you to add another boot config for it.

So when you make mistake, you can boot by another boot config.
(Re-create system.img or flash whole system.img take a lot of time.)
And rename your test file before you copy into target folder.

$ vi /boot/extlinux/extlinux.conf

LABEL primary
      MENU LABEL primary kernel
      LINUX /boot/Image
      INITRD /boot/initrd
      FDT /boot/<target>.dtb
      APPEND ${cbootargs} ...

+ LABEL TEST_KERNEL
+      MENU LABEL TEST kernel
+      LINUX /boot/Image_test
+      INITRD /boot/initrd
+      FDT /boot/<target>_test.dtb
+      APPEND ${cbootargs} ...

When booting to UEFI, follow the step to change boot device.
Or you can select the TEST_KERNEL boot config by typing '2' in console.

Boot from USB stick

Another way for safety boot is using USB stick boot.
Follow section: Flash demo image to create new USB boot device, when boot to UEFI select the right boot device.

- root=PARTUUID=ad43ec6f-6d79-4df0-b915-1c936b0e33ef
+ root=/dev/sda1
Otherwise, the OS might select the wrong rootfs device.

Remove/ modify the default user and password

In download script, we add a default user ubuntu:ubuntu

# vim technexion_jetpack_download.sh #Line: 274
        # create default user and auto login
        sudo Linux_for_Tegra/tools/l4t_create_default_user.sh -u ubuntu -p ubuntu -a
# -a stands for auto login.

This user can't be removed, so remove/ modify this line BEFORE you run the download script.