I would start fresh, pretend you are setting this up for the first time. (Assuming you already have found the best location for the extender, which is between your router and your problem area, but be mindful of any concrete/metal/fishtanks, etc, things that will block WiFi)
Plug in the extender, wait 1 minute for the Status LED to go green.
Enable WPS on the router by going to 192.168.0.1 and logging in with default info (if not changed), (I also would need your routers model # to tell you that info, but I am just finding this all off of google)
Somewhere in these router settings you will find a button that allows you to click for WiFi Protected Setup (if your router supports it - if not, we will cross that bridge when we come to it)
Press the WPS button on the extender.
Within 2 minutes press the WPS button on router (info above)
The SSID for extender should now change to (yourSSID)_EXT (shares same password)
You should now be able to connect to it.
If you can't, or if you can't find WPS in your routers settings, let us know.