I just got my iphone 6 3 weeks ago and now it's not charging. It died today and when I went to charge it, "This cable or accessory is not certified and may not work reliably with this iphone" keeps popping up. I eventually got it to charge but it won't go past 2%. Every time it gets to 2%, it goes back to 1%, then dies, then charges to 2%, then die again. How can I fix this?