Sending back broken laptop from ebay.?

My 4 year old laptop, recently died. so i turned to ebay looking for a lower cost replacement. i found one for a decent price. it came 6 days later than within 2 hours of use it died too....sort of. it starts but will not boot, and the screen is black. I contacted the seller she saud to send it back and will refund my $. being optimistic i contacted hp to see about repairing. they quoted me $250, with the diagnosis. i forwarded this info to the ebay seller, and didn't hear anything back. so im weary about sending back the laptop and her having my $ and the laptop. Any pro ebayers know what to do or have any suggestions so neither party gets...screwed? thanks.