No one connected to your pruchase of a brand new item on Ebay will replace or refund if your new electronics goes bad. Worse yet is that credit card additional warranties are based on the original warranty which is none. Doubling of no warranty is zero.
So, if you do buy from Ebay, make sure you accept zero warranty or purchase the Ebay additional insurance. Why? Because according to the manufacturer, Ebay sellers are not legitimate sellers, even when new in the box.