After upgrading to my Nexus 5 to Marshmallow, I find myself experiencing crashes regularly. The phone screen will go black, and attempts to restart will make it to the home screen for a few seconds before the screen goes black again (regardless of power levels). The only way to restore normal functionality is to hook the phone up to a charger, at which point it will boot without issue.
I have tried clearing up disk space, which did not seem to help. I have tried doing a factory reset (the one via "Settings > Backup & reset > Factory data reset"), but that also does not seem to have stabilized the environment any more. It doesn't happen at regular intervals, nor does it always happen with the same app. I have noticed that it often happens while I am using SuperCell apps (CoC or Boom Beach), but that my be correlation rather than causation. It has never happened while my phone is plugged in.
All this said, anyone have ideas on what may be causing it or diagnostic steps to take? I tried looking for logs, but haven't found much. Could also be a hardware issue and the update is a red herring, but thought I would ask those with more knowledge before writing my phone off as lost.