Why won't my s4 boot up

A

AC Question

I have completed a factory reset. Both in settings and holding the power button, volume up and action button and selecting from the start up page. I've also rooted and reinstalled firmware. It started up and allowed me to go through the options as if brand new phone but, the battery ran flat and when I turned it back on. It came up with Samsung logo and froze on it. Any help please