Don't turn it over for 30 seconds. Do it in shorter bursts of 5 to 10 seconds at MOST. Give the starter a few seconds in between to cool down. Try cycling the ignition off and on a couple of times. One other thing to try, and this is what you're not supposed to do, but it has worked for me at times on very cold mornings. While you are cranking the engine, give the throttle a twist.