NightHawk X6S AC3600 - trying to connect to my router - reply shows Offline

I am trying to access my NightHawk X6S AC3600 router to update with new firmware but I am stuck in a loop.  WHen I login - and I had to change my password - it continues to come back and show that I am offline.  Even though I am connected on all of my devices using the router.  How do I gain access to my router to update the firmware?

Thanks for any insight or help.