Why seller need take all the responsibility ?
@sjlin830
Your item was shipped through the eBay Global Shipping Program. Though the dispute lands "in your lap" so to speak, you should eventually not be responsible for this. Your job now is to contact eBay, and convince them that this was shipped through the eBay GSP, and it should not be your problem.
That is, of course, if your buyer filed an eBay claim and not a Payment Dispute (aka chargeback). In the latter case, the protections for you do not apply.
Good luck, and let us know how it turns out.