I don't know the asrock rma procedure, but it can't hurt to try, depending on your country of origin. I mail my rma's by parcel post for around $11 from texas. As long as your board has no physical damage or burn marks, they might accept it. Here is a link to their homepage: http://www.asrock.com/support/index.asp?cat=RMA.
Give them 24 hours to respond. Just tell them it won't post. Nothing more is necessary. They may or may not ask for an invoice from the vender. Some manufacturer's require it; others don't. It only takes a few minutes to fill out the form.