I understand your contemplation putting myself in the buyer shoes, but its unfortunate that things my happen, but i dont think its your worry if you know you sold it in good faith and working condition, you have no control over what happen to it during transit or setup. now that being said, I would request a video of it and me being me, if i could fix it i would have him drain the water and reseal it for him WITH HIS HELP and id supply the adhesive sealer. now if he water a refund... Not going to happen..