Have you done activating your modem with your internet service provider? If the modem successfully activated then you can try resetting modem since the LED is flashing blue. 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. 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 wait until your device fully boots up. If still the LED is flashing blue and the modem is under warranty please reach out to Arris.com/consumersupport for further assistance.