Have you changed batteries,cables,etc. And checked charger port and cable? Sudden death syndrome. Have you had any UID errors or programs deleting? Probably means the Emmc is dead . Happened to my phone. You have to replace the motherboard which is pretty easy. Ebay has note 2 motherboard for $20+. Of course you could try to desolder and replace the chip but its easier to just change the motherboard.