Iphone 6s keeps charging, dying, then restarting

I downloaded the new iOS update last night on 7/26/16. I woke up this morning and my phone had died, so I charged it. It will show the charging battery on the black background for a mere few seconds, then the white screen with the black apple, then my home screen for less than a second before it dies. It does this with every charger I own and goes through this cycle even when I unplug it. I tried holding down the power off button but by the time I have the option to slide to power off, it dies again. I have also tried holding down the home and lock button and nothing seems to work.