In the process of fiddling with your router settings, it sounds like the OBi was assigned an IP address, and you know what it is; is that correct?
If so, open a web browser and go to that IP address. The default user name and password are both "admin".
Are you able to open that page? If so, look at the left side of the page, and click on "Status" then "PHONE Port Status".
What does it tell you? With no phones plugged into the OBi, do the ports say "On Hook" or "Off Hook"? If they say "On Hook", then plug a phone into one port at a time. Without lifting the handset, what does the status say now?
Where did you get this OBi -- from Amazon or Newegg, or from Craigslist or eBay?