iPhone randomly resets itself
My iphone 6s always had the latest update installed however occasionally it resets itself. It happens while using the phone or while it's locked. It can happen while it's charging or while it's connected to my computer for sync. Sometimes it locks and I can't press or do anything and a few seconds later I see some random colors on the display and then it resets itself.
Sometimes, in the morning it asks for my "passkey after restart" so I know it has restarted itself during the night. These episodes seem to happen completely random, I haven't been able to re-produce them intentionally.
My phone is still within the 12 month warranty from apple but I don't know how the problem might be replicated if I send this in for warranty.
Any advice on how I could narrow this down? Maybe there are some logs that I could read to find out what happens? I'm afraid that if I send it in for warranty and it does not reset itself while in the technician hands they might send it back with no problem found.
I am windows user so I am looking under "AppData\Roaming\Apple Computer\Logs\CrashReporter\MobileDevice\" and I'm seeing lots of log files but I'm not sure where to look more precisely.