Performing reset will definitely take you to the modem setting page using default login credentials. Even you tried multiple reset we would suggest you to try hard reset on the modem for one last time and then try accessing interface using default login credentials.
To perform hard reset disconnect the coaxial cable from the back of the device? At the back of the modem, in the middle section you will see a small hole, inside that hole there is a button, and that is the reset button, please insert a paper clip or a tip of a pen and hold it for 15-30 seconds until all your lights go off, afterwards connect the coax cable back and wait until your device fully boots up.
But after resetting the modem will go to default setup any custom settings will be removed so use the default network name and password
to connect to your network.
http://arris.force.com/consumers/articles/General_FAQs/SBG7600AC2-Web-Manager-Access