GOT INTO MY BOAT TONITE, TURNED ON THE BLOWER, TURNED THE KEY AND CRANKED A LITTLE AND THEN LOST ALL ELECTRICAL POWER. NO LITES,HORN ,STARTER NO NOTHING. CAN ANYONE GIVE ME AN IDEA OF WHAT WENT WRONG OR WHAT TO CHECK. bOAT WAS RUNNING FINE ALL DAY UNTIL THIS HAPPENED. BTW 4.3L MERC.