Hopefully, proper 2 stroke oil was used, I'd rock the con rod, to see if it moves freely.
If correct oil was used, and crank is good, cylinder may have been poorly fitted at factory. Good luck on the Warantee, most vendors will try to pass it off as ' your problem, not mine ' Considering the lousy quality, vendors should be more receptive to factory fubars. The concept of tearing down a ' new ' engine, to see if was built right, is insane, but prudent. Before buying, ask vendor if they recommend a pre - fire up teardown, and if they honor warantee if [ when ] problems are found.