Seller not responding to messages, not honoring warranty on item

[paul_oz]

Contacted seller about a warranty issue. For a few days they were responsive, tried trouble shooting steps, etc. Did not fix issues. Then they quit responding for several days after I asked them about having it repaired under warranty. No response for severa day. The seller claims their eBay message center was down for several days. Then after I asked about warranty on my laptopagain they have quit responding again. The item is past the time period to open a case with eBay. What can be done about a seller that will not honor their advertised warranty?