Nighthawk RAX35 won't recognize internet signal on new modem...

Help please!
The technician set this up for me when we got our internet installed, so I am not sure what to do here.
My internet stopped working 10 days ago, and we've not been able to figure it out. I changed out the modem with our ISP and it is working with a hard wire to my computer, but that same wire is not being recognized by the router. It shows as an Amber light, and I can't do any of the things I have seen (update firmware, go to routerlogin, etc., because I cant get the router to recognize the network. 

Can anyone lep me please?

Thanks!

Tina