Turning on screen, flickering.. with logcats
The symptoms you describe sound much more likely to be a hardware problem than a software problem. You probably need to get the backlight of the screen replaced (or the whole screen, if it's an OLED screen).

You shouldn't have rooted your phone when it had an existing problem, if it was still under warranty. As things are, you'll need to pay to get your phone repaired. Take it to your local phone repair shop.