sold on ebay, customer refunded without any information

[mereuts]

Hello
I sold the item on ebay (gadget, 500usd)
the customer received the item and asked for instructions for use it
I sent him a message with instructions and he doesn't answer anymore

but yesterday I saw that he requested a refund.
what should I do so that the client does not keep both the item and money?

I am trying to select a transaction in the resolution center, but I get this message

We're unable to file a case on this transaction.

Since you’ve received this payment, you'll need to contact the sender directly to resolve your issue.

then I tried to write to support
and no one answers at the message center

[Airhaun]

I sold my old laptop on ebay 2 months ago. The buyer behaved strangely, took almost 4 days to pay then sends a msg threatening to file an ebay claim if the package doesn't arrive the same day UPS tracking says it will. The package was delivered on April 16th as UPS reported and I haven't heard anything since.... until a couple days ago. 

I get an email from Paypal informing me the buyer has filed a claim stating they opened the box and the laptop will not turn on, they claim they have repeatedly tried to contact me but they didn't receive a response and want a refund

It's been nearly 2 months since the laptop was delivered. I have not received any msgs on ebay, paypal or other personal email accounts from this person. In the paypal dispute, the buyer states they attached a screenshot as proof showing one of the attempts to contact me. There is no file, no screenshot visible attached to the dispute. I responded to the dispute with a detailed letter and 4 supporting documents attached (which are visible and clickable).

After a couple days paypal informs me they've decided to refund the money and have the item returned!

So apparently, all you have to do is start a claim, say that the item doesn't work and seller is ignoring you and PayPal will issue a refund. 

I am not settling for this and will be looking into it further. There is nothing legitimate about this claim and no justification for PayPal to take this money.