Nighthawk AC1750 setup stalls at routerlogin

Hi everyone. I'm a novice when it comes to this stuff so be nice. ;) I just purchased the Nighthawk AC1750 along with the Netgear CM400 HS Cable Modem in order to replace the jinky one from Comcast. The modem connected no problem. Then I followed the written instruction to install the router. I messed up when it came to the ethernet cord and instead of taking the cord from the back of the computer and plugging into the router, I unplugged the cord from the modem and plugged it into the router. I figured that out when it came time to plug an ethernet into the computer to have a wired connection. So, I unplugged the ethernets and tried again. Then came time to get the browser up to put in the password and whatnot. Firefox opened up about 4 tabs on its own, each one trying to detect internet connection. Internet connection failed. I tried rebooting the modem, I checked all ethernet cords. Tabs continued to spontaneously open looking for a connection to the routerlogin.net page. I turned off the computer, unplugged everything and tried again, this time following the instructions correctly. Still have the same problem. I'm certain it's probably a simple mistake, but I'll be darned if I can figure it out. So...does anyone have a direction in which to send me? Thank you!