XPS 8960, Killer 3100G ethernet failed?

I have an XPS 8960 that's still under warranty. It has a Killer 3100G ethernet port. System worked fine. Left it for the day. Came back the next day, system was locked up. Had to power cycle. After power cycling, the 3100G interface appears to be dead. There's no physical link light on the port, or the switch port it's connected to. I have tried new cables and a new switch. There's still no link light. I wasted over 90 mins of my time with Dell support. They did a remote access and I watched painfully as the tech support person tried things that had absolutely no bearing on the issue, such as clearing my browser cache and checking the anti virus settings.

Dell is refusing to replace the motherboard, insisting that it's a software problem because the device shows up in the Device Manager. I have tried removing the device, removing the drivers, rebooting, the device shows up again, and I reinstall the drivers. Still no link light! This has to be a physical device problem. The link light on these ports should come on as soon as power is applied, so it's not a device driver or OS issue. How do I get past the first level in support to get to someone who can actually resolve this issue and stop wasting my time clearing brower caches?