If it's new and was sold as new, they ought to be pretty good about exchanging or making things right. And even if they say No Returns, No expressed or implied warrantees of fitness or merchantibility, most states have consumer protection laws that support a limited Guarantee of Merchantibility. In other words even if you waive the warrantee on a new item sold as new, it is supposed to work as designed, it might not work for what you want ("Fitness") just works (merchantability). You should probably get satisfaction. Might not but you should. Buyers Remorse won't do, but a bad product should.
Now if it was sold as Used, As-Is, and you didn't check it out thoroughly and find the problem that was obvious, then shame on you (and maybe them for ripping you off), or if just buyers remorse and they let you know about the problem, well you are probably stuck It may help if you offer to pay for their time and paperwork costs. up front