Here you go:
How to use buyer protection
Within 2 days of receiving the item, use the Contact Us button at the bottom of this article.
Select Submit a buyer protection claim in the form and enter your reason for using buyer protection. We’ll also need your transaction ID to find details about your purchase. You can find it on your receipt. Open it from your messages about the item, or:
Log into your account
Tap Payments and receipts, then Transactions
Select the receipt for the item you have questions about
Scroll to Payment info for the transaction ID
OfferUp will review the request and take corresponding action. OfferUp may request additional information or documentation, and reserves the right to deny buyer requests.
On approval, OfferUp will provide return instructions, and the buyer will handle the item accordingly.
OfferUp will issue a refund up to $500 in the original form of payment.