I just figured it out. When uploading the system firmware to the board, just make sure DASH SYSTEM board and SYSTEM.HOLOGRAM.IO USB are used.
Most importantly, the INO file that is active on the Arduino IDE must be one of the sketch from the SAMPLE APP of the DASH SYSTEM as shown below (else you’ll get errors on some objects not ‘recognised’ by the compiler:
It’s like uploading an ordinary firmware in the DASH, but since SYSTEM is specified, the firmware will replace the system firmware and not the user firmware. You will know if you successfully ‘revised’ the DASH firmware when you upload your next user firmware and be prompted like the screen below:
Thanks to Maiky for helping me on this one.