Xi5 Box stuck on "Welcome" Screen

I picked up a couple of Xi5 boxes today to try to workaround some coax line issues in my house. I've got it connected to the WiFi network coming off of my xFi gateway (though not exactly by choice - seriously, Comcast, allow us to connect them to our own routers, please), but it's now stuck on the "Welcome - Connecting to Your Entertainment Experience" screen.

Any ideas?

P.S. I've gone into the diagnostic/service menu (fortunately the Xi5 uses the same access sequence the XG1v4 does), and I've got an IP from the router, but other than that I'm getting nowhere.