Chosen Solution
Last week I replaced the battery using your guide. Yesterday my wife dropped her phone (in a LifeBox case). The phone would not turn on or reboot. I opened the phone and found that the battery had shifted. I repositioned it and now the phone boots and works but the display is flickering. I tried changing wallpaper but no help.
Do a hard reset hold and press power and home button at the same time til you see the apple logo.. If that doesn’t work then you have damaged the LCD to fix the flickering you will need a replacement
I am going to put my money on the LCD having a broken connection somewhere. Flickering means it is getting an intermittent connection. Just my $.02. Good Luck!
