My Nexus 5 is restarting on its own. Not bootlooping - it is often able to complete the booting process and be usable for a few minutes before restarting again. This happens regardless of whether the phone uses battery power or is plugged in. Tried flashing it back to stock (factory images: KitKat, Lollipop, Marshmallow) - it didn't help, so it looks like a hardware issue. When first turned on after being idle for an extended period it usually works longer before rebooting, then reboots become more frequent.