Anyone have experience installing linux on first gen Aopen commercial Chromeboxes?

Just picked up a couple of first generation Aopen Chromeboxes from a recycling haul, originally intended for things like digital signage in businesses. They run chrome os but I’ve been having a hard time getting into any kind of developer mode on it. It doesn’t have a keyboard like a standard chrome computer, so no boot shortcut keys. I’ve dug through youtube but it doesn’t seem like many people have tried to get linux running on these things. Is it impossible? Or am I just missing something?

There should be a small pinhole button to get into recovery mode, from there take a picture of the recovery mode screen so we can see the model.

Found the reset button, it was unmarked and off to the side of the unit, just above and to the left of one of the side mounting holes. Here is a photo of the screen you get when you hold it down and power the unit on.

NINJA is on the supported devices list. To proceed, you would disable hardware write protection, then flash MrChromebox’s UEFI firmware and install Linux.

Awesome! Thank you so much for your help!