What caused it is simple. You had/have a corroded or shorted coax cable usually at the connection end and usually at the roof top connection. THAT caused a bleed of 12 volt current, not enough to blow the fuse, but enough to heat up the center copper conductor and cause the coax cable to heat and the melt. Whenever you turned on the Antenna booster that current then flowed. You need to find out why the CABLE input had such back feed of current as the Cable input should never have 12 volt current on it. Only the cable from the booster to the roof antenna should have this current. Doug