Hmm... It could be drained, or the update could have messed with the phone. I would try a few things. First, make sure the charger is actually working. Try it in a different phone, and also try a different charger in yours. If that doesn't change anything, then try locating the pinhole on your phone. It is the "Factory Reset" button. Using something small, but not sharp (as you don't want to damage it) push the button in that pinhole to see if it will reset the phone.