I'm having the exact same problem as stated by the previous people. I purchased a Certified Pre-owened iPhone 6s plus in December of 2018 that recently stopped working. I contacted customer support and was told this phone was still covered under the 1 year warranty. I was told that I would need to take it to an Apple store and they would fix it. The people at the apple store informed me that the phone's warranty expired in 2017 because it was previously purchased in 2016. They refused to fix it. I need boost mobile to contact me about this issue.