It is really lame that you can have an MT on top of a 100 foot pole and after you have manually wiped the unit's settings by going into each screen (fw, Hotspot, Universal, Etc...), the Hotspot setup refuses to configure the unit correctly. Then the only fix is a "system reset" and guess what? If you do this - you better start climbing because there is no default IP on the unit after a reset or even a mac-telnet capability. So bring a console cable and a climbing harness because guess what - Your going up the pole.
In my installation, the 150 feet long console cables made of STP cat.5 and connected to the router's serial port permanently, works perfectly. All my routers, installed on the masts or roofs, are equiped with console cables, and I can connect a notebook to it and get an access to console from the ground.
In your case, there is an another solution. Use an another router, for example a demo version of MT, installed on any suitable computer, to prepare the proper configuration (it can be just an empty system with properly configured eth0 interface), issue a '/system backup save' command, upload the generated .backup file from it and download it to the router, that needs the reconfiguration, then issue a '/system backup load' command. After this, all your old configuration will be erased and the new one will be installed.