Powering on

Hi. I have had to power cycle my atem studio pro 4k switcher.
Since there is no power switch, I pulled the ac out, waited 10 sec, and plugged it back in.
The device "set" light goes on, but nothing else.
Am I missing something stupid? How do you turn the device on?

You turn it on exactly the way you did.
It looks like it has problem with the firmware and are in recovery mode.
Connect it to your computer with a usbcable and run Atem setup to update the firmware.