Fiverr provides absolutely no protection to sellers. A buyer can have you do all the work and also have you make unlimited revisions for it until he is fully satisfied.
Get all the order files delivered and then simply say the simple magic phrase "Sorry delivery was not unto mark".
Now Fiverr support will very happily refund him all the amount no questions asked. It doesn't matter if you agree to give him refund or not because Fiverr support will not take a look at anything and simply cancel your oder and refund him the entire amount.