Offline c700 nighthawk

Bought this device in Sept. No issues until about 3 days ago. I now have no internet connection. Called isp and everything is fine in their end had a tech out who used a test modem and that worked fine they are saying the device is offline and logged into modem and it says it's offline. Spoke to netgear and they say device is working fine after ping test and checking the ip address but do not offer a fix without me giving them money. Any ideas or suggestions to fix this issue would be helpful. Have tried factory reset but to no avail.