Hello, this post is from a few hours ago now - did you get sorted?
Mine wasn't working all afternoon and am still waiting for a repsonse from customer services. I had same issue, setting up stick for first time and getting stuck on Get Started page. I believe it was an issue affecting a lot of people and Now TV were working to fix it, so hopefully your problem is resolved now.
I tried pulling out stick for a few moments but that didn't fix it. However, a few hours later I tried that again. Pulled USB lead from plug, pulled out stick from HDMI port on TV, turned off wifi. I left it for a good 10-15 minutes. Turned on wifi and then plugged in stick again. Got a blank, pale blue screen for ages. Put it onto normal TV while I waited. Turned it back onto Now TV screen and the Get Started page was back again. Clicked on Get started. Again. Worked!!! Started loading all the channels etc. We're watching it now. If it's still not working I'd maybe try that.