How to fix/remove/open a case for Negative feedback on sellers?Please help

[tarmourauto]

I recently received a buyer, who left a negative feedback for the product he purchased, and claim the the product doesn't work.

I ordered a full refund and allow him to keep the product so he doesn't have to return it. Then I sent a feedback review to him. It seem like he doesn't want to change. what options do I have? I just started selling on ebay, one negative feedback means a lot. I believe that I have provided the best service that could possible be given by a seller. 

Are there any method I can fix it?

So far after I did some research, only found "asking buyer for a feedback review" and "SquareTrade mediator"(this seems like has no longer providing the service), 

Please guys, I need help from you all.

[corgidogz06]

Check to see if your buyer has left excessive negative feedback for other transactions,  if so, phone ebay (don't email them or chat) and explain the situation. You would probably get it removed. At any rate, I would phone ebay and explain  what you have done for this customer.

[phorum_junkie*]

If you refunded then you presumably accept that the item was faulty. The buyer has left factual feedback and has no reason to revise it just because you refunded them.  Many buyers would consider revising if they got a refund but they are under no obligation to do so, the fact you refunded does not change the fact they got a faulty product in the first place.

Your best bet is to leave a short follow up, something like "Sorry, full refund given as soon as you told us" or similar would be best.

Many of us base our decision to buy not on if a seller has negs or not but how they handle them, in other words if they reply with capitals and name calling we avoid!

[bright.ton42]

Many of us base our decision to buy not on if a seller has negs or not but how they handle them, in other words if they reply with capitals and name calling we avoid!

Definitely. I do.  A calm reasonable response to a neg impresses me and I'll buy from that person.