Reboot triggers Poweroff

When I restart my computer from ssh remotely using:

sudo reboot

...it never comes back. I have to ask someone to go to the computer to physically hold down the power button until it goes off, then wait, then press the power button again to start it up again. The person reports that they find the screen showing a spinning symbol, likely the trisquel logo before pressing the power button.

Can someone recommend steps to debug this?