Phone shows in iTunes, makes no charging noise & screen is black?

I replaced my phone screen for the iPhone 6, did everything just fine (Ive installed many phone screens). I go to turn it on after letting it charge for a while before hand, and nothing happens. So I try a hard reset. Still nothing. I plug it into iTunes, screen is still black, but it shows up in iTunes? But, when I take it on and off the charger, no charging noise occurs whether on vibrate or the sound is on. It also doesn't make a noise when I flip the switch either way. I ordered a new screen again thinking it is the LCD, but I am really worried it is something else?