There are two issues here from what I see.
First there would be a tire warranty, which generally covers defects in material and/or workmanship.
Second there is (or MAY be) road hazard coverage which with some exclusions generally covers damage to a tire from road debris, nails, etc.
A sidewall blowout is MOST OFTEN caused by damage to a tire from running over a curb or other debris in road, or over or under tire inflation, generally NOT caused by defect in material and/or workmanship.
That being said, if you don't have the tire still, all bets are off, I don't think you will get anywhere with manufacturer. If you purchased a road hazard plan on the tires, they should cover the tire. If you did not, I don't think the manufacturer will do anything, because, frankly, I don't think they did anything wrong. . . . Sorry to be so blunt, but sometimes things happen, and no one is really "at fault". So just be thankful no one was hurt, and move on!