Tell them to plug it in and turn on the switches, usually helps LOL. OK on the seroius side always hard to tell weather they are telling the truth or trying to get a refund while keeping the item, have they opened a return request ? , i would ask them to make a short video of them showing the item plugged in power on and starting the machine or not staring as the claim is, not hard to do with a smartphone and can be uploaded to Ebay messages, this weed out the truth of the matter, if you do not hear back from them, forget it and move on.