WiFi extender Nighthawk EX7000 won't connect to the network wireless or with ethernet

I can't call tech support because it won't let me register it. It says the unit was already registered. I bought it refurbished and it looks like the previous owners had the same problem. They probably bought it, wouldn't work, registered it to get tech support and then returned it. Now I can't do anything with it and it obviously wasn't repaired correctly. Unfortunately since I spent so much time trying to make it work now the place I bought it won't take it back either.