So I have a Nexus 5 recently updated to the Marshmallow update. Though I like the interface I've been having serious issues with my phone randomly booting down. Sometimes it restarts on its own, other times it takes a few tries before it wants to turn back on for me. It's very frustrating as I run a business and use my phone a lot. Note: My phone is in great condition and have never had these issues prior to the update. What can do I do about this?