Arris S33 shows only solid white

What is solid white? A certain led? Which one?

Are you able to log into it? 

Could you factory reset the modem once and do self-activation through Xfinity application.

http://arris.force.com/consumers/articles/General_FAQs/S33-Factory-Reset

Also check the IPV4 address through direct connection.

Turns out my S33 was busted. The Xfnity website kept saying there was an outage at my house. But the Xfinity tech guy came anyway, had his own modem and router, and showed me that I do have service to the house. And a broken modem. It was under warranty and Arris will replace it.. so I’ve sent mine back to Arris in Oregon and they’ve received it. But they say they don’t have one on hand  to send me. Still waiting. For days. Can you believe that????

Since the modem is defective, Arris offered you the replacement under your warranty claim.

You can anticipate receiving the replacement as soon as the inventory returns to normal.