Won't start after unwanted shutdown

Started up to mow. It ran for about a minute and came to and abrupt stop and died with a loud noise. I originally thought I ran over something. Moved the lawn mower to look at the blades and found no obstruction. Tried to crank but the fly wheel would not spin. I was able get the flywheel loose and the starter will spin it when trying to crank. I replace the fuel line and filter in addition to cleaning the air filter and also changed the oil. There is no fuel pump and is gravity fed. I cleaned the sparkplug and did a visual test by grounding and watching. The plug is sparking an orange, blue, and purple so it appears to be fine with an occasional fire off center. I removed the carburetor and cleaned it and still won't start. I removed the face plate and turned the flywheel by hand. I was able to see the carberator and exhaust piston cycle as expected. The power piston does not move, but that should keep it from starting if I'm not mistaken. I cleaned the carburetor a 2nd time and it still won't run. Since I have ordered a new carburetor and will install when it comes in. I was hoping someone can point something else out in the mean time.

Engine: Briggs and Stratton 15.5hp
Model 28V707
Type 1113 E1

Loud noise = something broken
Could be the con rod, counter weight, flywheel key, cam oil pump no idea
Briggs make 2,000,000 engine a year and have done so for a long time
They make around 50 different models.
So if you want more from us we need more from you.

Humpty Dumpty made a great noise,
Humpty Dumpty makes no more noise.
All the carb cleanings and all the all the oil changed,
Couldn't make Humpty start up again.

Cleaning the carburetor twice and then buying a new one is not going to put this Humpty-Dumpty mower back together again. What you're doing is the equivalent of washing and waxing a car after it's slammed into a tree at 60mph--not hurting anything, but not helping anything, either.

As was said by bert, loud noises are made by big time collisions of parts that are not supposed to collide. Check to see if it has compression. That's Step 1.