What can I do if Amazon refuses to refund me?

A return window closing does not end your rights over goods that were defective. In every state, goods sold by a merchant carry an implied warranty of merchantability: an automatic, unwritten promise that they are fit for the ordinary purpose goods of that kind are used for. Nobody has to say it or write it, and a retailer’s return policy does not, by itself, disclaim it.

If what arrived was materially different from the listing, that is a separate and often stronger claim. A description of goods and any statement of fact about them becomes part of the bargain and creates an express warranty, and a materially false listing is also an unfair or deceptive act under your state’s consumer protection statute. Screenshot the listing before it changes, because marketplace listings are edited routinely.

Run a card dispute in parallel rather than waiting for Amazon to say no twice. If you paid by credit card, the Fair Credit Billing Act gives you 60 days from the statement to dispute in writing, and it runs on its own timetable without needing the seller to cooperate. Third-party marketplace sellers are worth identifying explicitly, since who actually sold the item changes who you are claiming against.