You only have 30 days to open a return through Ebay.
Message the seller again and, if they were a business seller, look up their details on their current listings so you can ring them and possibly write to them.
The warranty is between you and the seller. Ebay will not get involved.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)