As ypdc_dennis says, your option to ask ebay to step in will appear tomorrow. The seller has until the end of business day today to solve the problem with you directly, before ebay will allow you to escalate the case and ask for their assistance.
It sounds like your seller is trying to avoid responsibility for fixing this.
ebay will help you but be sure to pay heed to their instructions on what-to-do next and whatever you do, do NOT allow the seller to sweet-talk you into 'closing your case to get a refund'. That is not how it works. That will leave you with a non-functioning blanket and no refund.
Best of luck to you.