The Defend-O-Tron will periodically update via the Debian package manager as shown on the administration interface under Software Updates. This utility is only required if you want to flash a new device or fix a disk failure.
You'll require an SD card imaging utility to start and a microSD card, preferrably 16GB - 32GB.

You can download the Etcher utility from here https://etcher.balena.io and install it.
The firmware images for the Defend-O-Tron can be downloaded from here https://firmware.awesome-o.cloud
Firmware:
Download the firmware image and burn it to the microSD card (at least 16G) with Etcher.

Once Etcher is complete flashing the SD card, Windows may display a disk and give a popup window saying each disk is un-recognized, click cancel.
If you accidentally click format disk you will have to re-flash the SD card again with Etcher.

The MASK ROM button allows the device to bypass booting from the internal eMMC disk and look for a bootable SD card instead.
This serves a few purposes:
The Mask ROM feature is meant to be protected physically. Keep the device secured and away from any unauthorized personnel who could access it with this method. Gaining physical access to any device, not just the Defend-O-Tron can allow bad actors to penetrate or exploit your security equipment.
You have to mask boot the device with the SD card inserted correctly in the slot, which is located on the side of the unit. This is best done with a monitor, keyboard and mouse attached.
The eMMC MASK button is located on the side for revision 1 of the unit.

The eMMC MASK button is located on the front for revision 2 of the unit.

Do not cancel the process or it will leave your Defend-O-Tron in an unstable and/or unusable state
When the setup is completed you can browse to the admin interface and continue with the admin-interface setup.