Did the fuse blow again? Perhaps one of those big breakers near the batteries with the push to reset buttons has tripped. The gen starter may be connected ahead of the breaker so thats why it will crank. Once the AC comes from the genny, the converter is producing 12v and you get 12v stuff to work. The relay may make a different sound for ON than it does for OFF. If it wasn't moving, it wouldn't make any sounds.