Upgrading firmware
v.f.The Regenbox's Arduino (should) come pre-installed with goregen firmware, but in case you want to replace or use a new Arduino board, or if a major version is released requiring firmware upgrade, or if you used the original console program regenbox.ino, you'll have to upload goregen firmware on the board by yourself.
You can achieve it using the Arduino IDE - this step first requires that you have drivers installed for your Arduino board, see the drivers section.
From https://www.arduino.cc/en/main/software
Launch Arduino IDE, and open the file firmware.ino shipped with your release of goregen
From the Tools menu, you need to select the Arduino Nano board. You should also see your plugged-in Regenbox in the Port section, if that's not the case, chances are you don't have working drivers installed; if there are several items here, you need to find & select your Regenbox among the entries.
Click on the Upload button in the top-left section (the right-pointing arrow), a successful attempt should take about 5 seconds, and look like that:
That's it, you can now launch goregen and expect craziness