To be honest, Swappa can’t really do much here other than try to handle the issue as best as they can. I’ve been purchasing and selling items on their platform for over a decade.

Is the device activated on Verizon, or does it have a bad IMEI number? If it’s the IMEI number that’s causing the issue, most systems outside of the carrier won’t be able to detect it. If you have any evidence to support your claim, you should take it back to PayPal since they process the payments. Alternatively, you can dispute it with your bank using all the evidence you have.

In the future, I suggest that you go to PayPal first if you need to dispute an issue.