My 6s has been acting up weirdly lately. The iPhone automatically self-resets when the battery is around 40-50%, then shows ~10% upon the completed reset. I also notice sometimes apps crash and the iPhone as a whole seems sluggish. Yes, I tried doing a clean install. What's even more perplexing is that I did get my battery fixed/replaced under the battery replacement program (free) for the 6s. I'm not sure what's going on here - and it's not under warranty anymore. Any suggestions?