Download the DietPi image for the Odroid HC1 / HC2 / XU3 / XU4 / MC1:
https://dietpi.com/downloads/images/DietPi_OdroidXU4-ARMv7-Buster.7z
Burn it to the SD card with Etcher
Right click and download the following two files: dietpi.txt, Automation_Custom_Script.sh
Copy them to the /boot directory of the DietPi SDcard

dietpi.txt: Overwrites the default dietpi.txt. Modified the settings to automate the DietPi setup. (see the details here)

Automation_Custom_Script.sh: Runs after DietPi installation is completed. Contains the link to download and run the build_sdcard.sh from the dev branch of @rootzoll.
(Optionally open the file with a text editor and uncomment (remove the # from the front of) the line with the branch you want to build the SDcard from.)
Assemble and boot the Odroid

Insert the SDcard, connect the HDD, network cable and power supply to boot.

The automated setup will continue and the Odroid will restart at least twice during the process.

To follow the logs during the automated building process login with root and press CTRL+C.
tail -n1000 -f /tmp/DietPi-Update/dietpi-update.log - follow the dietpi-update process
tail -n1000 -f /var/tmp/dietpi/logs/dietpi-automation_custom_script.log follow the output of the build_sdcard.sh
When the setup is finished log in as admin:
ssh admin@[IP-OF-RASPIBLITZ]
password: raspiblitz

The setup continues with the RaspiBlitz Setup Process

For the Odroid HC1 / HC2 / XU3 / XU4 / MC1 the start is this image:
https://dietpi.com/downloads/images/DietPi_OdroidXU4-ARMv7-Buster.7z
Burn it to the SD with Etcher
Insert the SD card, connect the HDD, the network cable and power supply to boot up the Odroid:
In the desktop terminal on Linux / MacOS or Putty on Windows:
ssh root@[IP-OF-DIETPI]
password: dietpi
Getting started with DietPi: https://dietpi.com/docs/install/#4-first-logon-on-dietpi
In the DietPi software menu install fail2ban and make OpenSSH server the default SSH server.
Ok > Cancel > Cancel
Search fail2ban > Space to select > Enter
SSH server > switch from Dropbear to the OpenSSH-server
Install > Ok
Reboots again
Log back in:
ssh root@[IP-OF-DIETPI]
password: dietpi
Changing the SSH server will change the SSH keys. To clear:
ssh-keygen -f "/home/[your-linux-username]/.ssh/known_hosts" -R "dietpi.IP"

Run this command to build from the master branch of @rootzoll:
wget https://raw.githubusercontent.com/rootzoll/raspiblitz/dev/build_sdcard.sh && sudo bash build_sdcard.sh
This will take a couple minutes depending on your internet connection and the processing power of the SBC.
Format of the command to build the SDcard from an alternative branch:
wget https://raw.githubusercontent.com/[GITHUB-USERNAME]/raspiblitz/[BRANCH]/build_sdcard.sh && sudo bash build_sdcard.sh [BRANCH] [GITHUB-USERNAME]
If you are working from a forked repo be aware of that the fork needs to be called raspiblitz for the git downloads to work.
Restart when done and log back in now as admin:
ssh admin@[IP-OF-DROIDBLITZ]
password: raspiblitz
From here he setup continues with the RaspiBlitz Setup Process

⚡️ RaspiBlitz-on-DietPi ⚡️

For the Odroid HC1 / HC2 / XU3 / XU4 / MC1