Xperia not turn on

[ala]

I have download latest software as given by update center then after clicking ready to install phone shows process up to optimizing app then after it initiate to start by showing flashing light and automatically turned off now im trying to turn on but it doesnt turn on 

[Uliwooly]

Connect your phone to a wall charger > press and hold power & volume up for 10 seconds > let it charge for 1 hour > try again