Jinlun Roller doesn’t start anymore

Hello, the scooter was standing for 3 weeks, then he drove for two days and then I refilled petrol from the can. The petrol was about 3 weeks old. If the scooter was filling on and then he suddenly went out and now I can’t get it on anymore. So about 20-30 times start it goes on and then shortly after it goes off again. So now a few technical data: Ignition sparks is there fuel comes carburetor cleaned new spark plug in ignition time also ok now I don’t know more further, could it be the cold starter or maybe something completely different????? Year of construction 2005 KM stood about 2300 4 clocks would be really great if someone could help me many thanks already in advance