unresponsive NEW EXTENDER SETUP button - Nighthawk X6S AC3000 EX8000

Nighthawk X6S AC3000 EX8000.

Couldn't find password so I did factory reset.
After factory reset
the farthest I got was a page with NEW EXTENDER SETUP button.

(192.168.1.250/login.html)

Pressing that button did absolutly nothing aside from tempraly changing color.

Tried wireless/cable. Edge/explorer/chrome.

Reseting again doesn't help.

Any idea?