My base station says i have to upgrade to airport utility 5.6 to update the firmware to 7.3.1 and it wont let me do anything.

This version of AirPort Utility requires this AirPort Extreme use firmware version 7.3.1 or later. Use AirPort Utility 5.6 to update this base station. AirPort Utility 5.6 is available at AirPort Service and Support. It wont let me into the router to do anything it just comes up with this everytime. I even tried reseting the **** thing and it still comes up with this. Anybody please help.