It should be quite easy to prove. As long as it has no visible damage on the outside. The water sensors could be a real problem as there have been reports of them going off in humid surroundings. But other than that, you're pretty much home free.
Unless there is visible damage (or water) they can't do a whole lot, as there is no proof that you have not used the product according to the funny piece of paper stating that you shouldn't poke the iPad screen with something sharp.
Unless there is visible damage (or water) they can't do a whole lot, as there is no proof that you have not used the product according to the funny piece of paper stating that you shouldn't poke the iPad screen with something sharp.