I see that occasionally and all I can do is refund them and move on.
On a very few occasions there is something wrong that isn't user error.
Had a Meteor cylinder that wasn't round inside once for an MS660.
Had a batch of Farmertec MS250 complete engines with improperly milled engine pans.
Had an 024 NWP cylinder with plating so irregular that there was bare metal in some areas, the other four of the same model in that shipment were flawless.
Had a big batch of OEM Stihl MS192T cylinders with improperly secured pistons that all arrived with one broken ring each.
In every case the vendor made it good.
But I just don't feel right asking a manufacture to warranty something that is likely the fault of the end user, just gotta eat it and smile.
Dave