Hi all, hoping to get an idea of what could have happened. My son was driving boat home for 2.5 hours and about 300 yards from shore we went to trade places and I tried to stop him from moving since kill switch was on his loop. We were moving about 5-10mph and the boat started to try and keep going with kill switch out. I even tried to push it to keep it going, but we were too slow to get the lock in place. After engine wouldnt start at all and got a tow in after some hard paddling. Any ideas? I noted that the tachometer is stuck around 4500 and wont move from attempted turn overs. I checked all fuses and removed one spark plug thinking it might be fouled. I appreciate the help. im pretty new to boat mechanics. Thanks!