What recourse is there for a phone that works poorly with a private seller?

Question

Hello, 4 months ago I bought a brand-new, still sealed Samsung A23 phone from a well-rated private seller. At first, no problem. I only noticed a lag in the display on the so-called digital navigation buttons at the bottom, and in the volume when I press the buttons. I chalked that up to the phone or the OS, it’s not an S after all, and it may not even be related to my problem.  Anyway, pretty quickly Android предложed me an update to One UI 6.1, which I did (again, maybe no link...), then...

*miss-tigri* · Accepted Answer

Hello  The only recourse would be through PayPal, have you tried opening one there? https://www.paypal.com/fr/webapps/mpp/problem-purchase   On eBay, nothing more can be done....