How do I re-activate (wake?) the monitors from the command line
xset dpms force on
If you have a more complicated system where you need to wake more than one display, you could iterate through them with something like this:
for display in `ps aux | grep -oE "/usr/bin/X\s[^ ]+" | cut -d " " -f 2`; do
xset -display $display dpms force on;
done
I don't expect this to work for many people, but if you're having the same problem as I was having on Ubuntu 16, this will work over SSH (not sure if you need X11 forwarding):
sudo unity-control-center
somehow did it.