I would ask what you would want a seller to do if you found a fault on an item (which, had you known the full and accurate description for, you would not have purchased), and would you be willing to lose your money because the seller was not aware that the fault existed?
I can appreciate that there was no intention to mislead, but the fact is, using someone else's description when you can not verify the truthfulness of it is always a risk, and not accepting returns doesn't actually extend to instances where there is a fault with the item, or it's not as described, rather it specifically relates to whether you're prepared to accept a return for any reason at all (or no reason), and under what conditions.
I would try to work it out with the buyer as professionally and amicably as possible. I'd personally accept a return and grant a refund if that's what they wanted, or negotiate a partial refund if they were still happy to keep them.
