I'm no Dad but I have some advice.

First off keep your cool. Even if you think you are cool, he is probably sensing your frustration. You have already taught him the basics. Put him in the yard with the bike and leave him alone. He will learn. He'll remember what you said and he will use it to teach himself. If you can get him to ride a girls bike, that will help too. It will be easier for him to get on and off the bike.