I also had a similar issue, my

husband bought a brand new boxed Samsung phone from an Ebay seller who had 100% positive reviews. He had it for around 2-3 months and all of a sudden yesterday Samsung locked it and he cannot use it.
He has emailed the ebay seller [seekvalue] who appears to have stopped selling items and he has heard nothing. Because it was over the 30 day period he cannot exchange it through ebay and get his monety back. He has paid the full price and there was no device trade in from my husband's part. So it must be the samsung reseller who did not perhaps trade in a phone or pay the amounted required.

I contacted Samsung but they are saying the reseller needs to get in touch with them to resolve this. The ebay seller [seekvalue] is not responding to messages via ebay. So, we are assuming that this plan is not going to work. Because it is 30 days after the phone was bought ebay is not going to do a return and refund, we are going through paypal but so far no responce either. Has anyone had this experience and how did they dealt with it?