Access to the requested page has been denied. ACCESS DENIED

I have a Nighthawk Model RAX54v2 (that's what it says on the bottom of the router) that will not allow me to access it anymore. AX5400 RAX54S (that's what it says on the box that the router came in)

I cannot give you the firmware version or anything like that because I only get "ACCESS DENIED"

I know the password; it's on my key chain.  It made me reset the password anyway. I answered the security questions and reset the password.  It still says "ACCESS DENIED".  I unplugged the router and unplugged the modem, even though the modem has nothing to do with this problem because it's on a completely different network layer, I did it anyway b/c I know someone will ask me to. After both the router and modem rebooted I still got "ACCESS DENIED.  Yes, I tried it with 4 different web browsers. Yes, I tried 3 different computers. Yes, I tried over wifi AND ethernet.  Yes, I rebooted my computer.  Yes, I tried to connect to it with the modem disconnected from the router to completely eliminate it as a variable.  Yes I tried accessing it through the default gateway. I only come to a forum after I have exhausted all troubleshooting techniques I can think of.  Please, do not make me reinvent the wheel.

What do I do to gain access to my router again?