Paying buyer is qualified to judge seller.

Buyer: stuff is broken.

Seller:

Hello and thanks for the response. We just have to ask a few thinks from you. Most of the time when we have a return we have to ask for the item to be returned of course to ensure it is the same one we sent out, we do mark all items in 5 spots with an infrared marker. Also we do have to ask for a photocopy of you're technicians license to ensure you are certified to handle these parts as if the part was not handled correctly or incorrectly installed and died upon first use then we cannot be held at fault.

Buyer: negative fb:
Item Recieved Broken Seller Refuses To Replace Buyer Beware

Moral: don't assert judgment over buyer's qualifications. Once buyer pays, buyer is qualified to judge you.