Charge back after item was shipped, unsure of next steps

[JoeUrban]

Good evening, I sold an item on Ebay and a day or so after I shipped it I got an email from Paypal saying the buyer had done a chargeback due to unauthorized purchase.

The email from PayPal said "Our records show tracking information is available for this transaction. We will review this as soon as possible. At this time, we need no further action or information from you. "

But the resolution center says they're waiting for me to respond:

"To help us resolve your case as quickly as possible we'll need you to respond by November 16, 2020 at 2:14:15 AM MST."

If he's claiming the card was used fraudulently it seems I wouldn't be able to give any evidence whether that is true.

So my questions are

- Should I respond as I have no evidence as to whether his card was used fraudulently and PayPal indicated they already have the tracking #

- Should I give my opinion about the likelihood of fraud (The "fraudulent" purchase is being delivered to his registered address, the item he bought is basically all he buys according to his ebay feedback, and his profile photo is of the type of item he bought and buys) or should I just not go there.

Thanks!

[JoeUrban]

Update: 

The buyer actually contacted me today saying he got a message from his bank about a security issue with the purchase.  It seems his bank decided that the first 10 characters of my paypal registered email address was my 'username' and since that didn't match my ebay username then there must be fraud happening and auto-reversed the charge... I've asked him to send me what his bank provided and then if he does I may just call Paypal since the web-response forces me to just provide tracking info with a comment and they already have that.