Power cycle means remove the power for 15 seconds, then reapply. It is one way to reboot the OBi.
Plug in the ethernet cable between OBi and router. Power cycle the OBi. Log in to your router and find the IP address that it has given to the OBi. Put that address into a web browser. Enter admin and admin at the login prompt.
In the left hand column click on Status, then Phone Port Status to get a screen like I've shown an excerpt from below.
Start with no phone plugged in. Then plug it in off-hook. Then take it off hook. What do the first four lines show for all three of those conditions? The page does not auto-update. You need to manually refresh it each time you make a change.