Returning to original firmware after ExpressVPN R6700v3 — Nighthawk AC1750 -

After getting back in a text chat with support for another 1.5hrs the solution took about 5min.

I hate how it took that long but here it is. 
They suggested I try expressvpnrouter.com:8080

expressvpnrouter.com is how you access the router dashboard/interface 

the :8080 didn't work but I got the idea to try the routers ip address and :8080

This worked!

For example 192.168.123.1:8080 in my browser

This took me to a different interface that was dd-wrt. I was easily able to login as admin with my same admin and pass and then uploaded the most recent firmware. 

Initially this didn't work.

I uploaded the file and expressvpnrouter.com was no longer accessible, nothing was couldn't do anything. When I checked what the ip address of the router was it was the same. 

So I decided to reset it, bingo once it loaded up I had netgear firmware/interface installed.

Wish they would have told me about :8080 from the beginning, would have saved at least 2hrs of my time.

Hope this saves someone elses the time.