Are you sure it isn't amber?
More details are needed though.
What are all the led's on the front doing? (color, blinking, solid, etc)
You're able to access the gui from the browser? If so, can you log into the connections page for the modem part of it? What does it show? (screen snip preferably)
If you contact your ISP are they able to see the connection to the modem?
Is the wifi broadcasting?
Devices are able to connect over ethernet to the router?
Have you tried disconnecting and reseating the coax cable? Maybe that was damaged/loosened in the fall.
Here's the support site that has access to the manual that has info on leds and ring light led meanings. It also has troubleshooting.
https://www.netgear.com/support/product/CBK40.aspx
Unfortunately, the fancier equipment gets, the more sensitive it gets. it might have seemed like a small fall but it doesn't take a lot to break delicate electronics. Hopefully its a simple fix/problem but there's always the potential something snapped off/broke internally from the fall.
