How the power button is supposed to work?

[Keex]

I got the Pine64 2GB and flashed Android 03032016 image and it's working great so far. 

For the push button, I connected it as a power button. When I push the button with android running, the display goes blank but the red light on the Pine64 stays on. So, it seems to continue to be at running state but no display. But I don't know how to bring back the display. If I unplug and plug back the power cable, it reboots just fine.  

Could anyone explain how the power button is supposed to work on Android?

Press it harder! Or better, a bit longer, like a second or so. This will bring up a menu with the options to reboot or to shutdown.

I would guess that pressing it short enabled standby or hibernate or something along these lines, but I don't seem to find a way to wake it back up.