C7500 - Ethernet not working

All of the Ethernet ports stopped working on my C7500.  I've tried the 30-second and 2-minute factory resets; the latter was suggested by Netgear support.  No dice.  None of the ports light up or transfer data, no matter how many different cables and computers I've tried it with.  I've also tried reprovisioning it in order to re-download the firmware from Comcast/Xfinity.

The WiFi works fine, but I need an Ethernet in order to connect my Plume mesh network to the Internet.

Is this thing toast, or is there something else I can try to get those ports working again?

Thanks!