You have verified that it has good ignition, and you have cleaned out the fuel system including the carburetor. There has been a ridiculous amount of fuel in the crankcase and cylinder, and it won't start until they are removed. That is normally done by pulling the starter quite a few times with the fuel shut off, the spark plug removed, and the throttle open. When you are fairly confident you've dried out the engine interior (you'll probably be able to tell by the decreasing amount of petrol smell when you pull the starter rope), you should leave the fuel turned off and squirt some fuel either into the spark plug hole or into the throat of the carburetor. If it won't start as a dry engine with priming, the state of its compression will come into question. However I'm hopeful that you haven't yet dried out the flooding, and that's all that's wrong.
