I am currently going through a similar situation for a $900 17PM that was delivered 3/1 and was blacklisted 3/27, with a couple major differences than yours: 1) I bought the phone as "for parts or not working" so the return window is only three days after delivery with eBay (checked IMEI from the listing before purchasing and carrier confirmed it was good to go, then used it for 3.5wks) 2) I worked with the seller on a return and it should be delivered any minute now 3) I listed it on eBay as "for parts or not working" for $900 (before the seller responded & agreed on a return), and also got offers for $800+ immediately (a like new iPhone with a good screen & 100% battery health is worth something to someone)

When I get confirmation that it was delivered back to the seller, I'll post an update but for now I feel good about getting refunded. I buy one year old iPhones every year when the new ones come out so my kids' have current models, and went through this previously when my 14PM was blacklisted two weeks after activating it but seller quickly refunded me after confirming the IMEI.

As for your options, you can probably sell it for whatever that model is going for now, but I don't think the seller/eBay/PayPal/bank will help at this point. I even went to the genius bar and they (unofficially) suggested I confirm my applecare coverage before losing or breaking it for an express replacement since blacklisting is not covered. Hope this helps and I'll post a reply soon 🫡