It sounds like you have bought from a private seller, since only they are allowed to have a "no returns" policy. But that applies only to change of mine returns of non-defective items, which a business seller must accept.
But none of that matters to you. There is a link beside "new" or "used" on the listing page to explain how ebay intend that to be understood. For both of those it has to be fully functional. No kind of seller can exclude liability for that, or make you pay return postage.
Remamber, when a case is open he will have to refund you, or ebay will almost certainly do so at his expense, If you are only communicating by informal messages, he is in no danger untill you open a case, which you might not do.
That thirty day clock stops when a case is opeded. ut for a mere exchange of messages, it is still ticking away. Some will to run you out of time with excuses and false promises.
