You can use the Click-to-Join link at the bottom of the page to get the option to upload images from your PC. It doesn't matter because I can read the numbers. Your signal levels look good. Skip the factory defaults for now.
What do you mean by not being able to "activate" your modem? Do you get Internet connectivity? The boot reads Locked, OK, Operational, Enabled, Allowed. All good things.
If you're not getting Internet connectivity, try wiring a PC equipped with a LAN port directly to the modem. If you can connect, this may be an issue with your router. No big whoop but let's first see if your modem gets Internet connectivity.
I'm wired directly from modem to PC - same issue, web browser redirects me to Cox's page that says my device is not activated, and hitting the activate button gives me the 403 error saying the server understood the request but refused to authorize it. Can't access any other webpage, just get redirected.
For troubleshooting, there is a reboot, reset and reprovision. You can reboot (unplug) and reset from your Cox account. A reprovision may fix your problem; however, only Cox can reprovide your account. It's deleting your privilege for Internet service and then recreating it.
I recommend sending an email to firstname.lastname@example.org. Just briefly explain what you've done to no avail so perhaps a reprovision. They can look into your modem, signal levels, your bill is paid, etc.
I think you need to include your name, address and perhaps phone number in your email. You could do this over the phone but the holding stinks and you don't know who or where you'd be dealing.
Chat is a nice feature but I think it's just a bot.
Hello, there should not be any spaces in the MAC address. If it was entered this way, it was done in error. Please reach us on Twitter at @CoxHelp, visit us on Facebook, or email at email@example.com. Provide us your name and the complete service address. We can assist you there with correcting the concern. -Dan