Dell 7000 laptop display has stopped working

The display on my daughter's 7000 is no longer working. Display to an external device (HDTV) is working. Nothing I have seen online seems to resolve the issue. The device is under warranty but I'm having a hard time figuring out how to make a simple warranty call.

Anyone else have this issue, or any pointers?

I've tried the display hotkeys to no effect, restarted the device with and without and external device attached. Even after a hard power off and back on, I get nothing on the screen. No BIOS / boot messages, no indication whatsoever that the screen might even have power.