Ebay KL paypal case?

I sold my notebook on ebay KL and after 2 days he wrote me
buyer and thinks the notebook is broken. I asked to try different solutions and give me a detailed report, but instead she opened a PayPal case against me and would like the money back.
The notebook has less than 200 charging cycles and was in a very good optical and technical state and I had no problem for years.

The buyer only claims that the goods are broken. But she probably just wants to rip me off or her money back.
If there's any damage there, can't I just sit there?

What options do I have? Especially what I have to say about PayPal?

Especially what I have to say about PayPal?

It doesn't matter at all:

If the buyer has paid for goods & services via PayPal and opened a buyer protection case due to a different item, then PayPal decides 99.9% for the buyer and your money is gone.

And you can then transfer the money to the buyer for a tracked return shipment to get your notebook back.

If you offer Paypal then you will also surrender yourself according to their terms of use.

Your options: none.

If the money from PayPal is already in the bank account, you can do little. They do not have to decide whether the purchase contract is void or not.
If you are a private seller and have excluded warranty, you are off the hook anyway, at least legally. PayPal likes to act as a judge.

Do you have witnesses that the notebook still worked when it was shipped? That would be good, best of all an unbiased witness.
In addition, he should first prove the defect, for example with a video