Turns a bit then stops then turns a bit and stops is most likely either a hydro lock or valve lash out of spec
First confirm that you can turn the engine over by hand by rotating with your palm on the debris shield.
If not then pull the spark plug & try again
If petrol gushes out then you have a hydro lock & the carb needs a clean because the float valve is not shutting the fuel off.
If you can turn by hand & no petrol comes out then see if the starter will crank the engine, should be very fast .
make sure the spark plug is grounded and out of the way lest you want a flame thrower .