New but dead iphone 11

Salesman nformed that iPhone 11 battery was flat. Salesman didn't have charger. Took phone on good faith. After charging for several hours phone refuses to switch on. Returned item. Salesman apologetic but manager insists that phone was dropped and sent it for assessment. If phone was 'off' at point of sale, how would the opinion of manager be sustained if determination is made that phone was indeed "dropped".