The author had a theory: "I’m still not sure how the scammer was able to open and close cases on my behalf. My theory is that they were able to spoof my phone number and call PayPal support and do it over the phone. (They asked early on for my phone number “for the tracking information,” which in retrospect doesn’t make a lot of sense.)"
In my experience, you can log in to Paypal/eBay by supplying your email address, then choosing "another way to sign in" (other than PW), at which point you're prompted to enter a single use code sent thru SMS. So: phone spoofing sounds likely, and it's my guess the scammers were operating without even having to use Paypal support to close the tickets.
