Chosen Solution
I recently got an iPhone 6s with a pretty badly damaged screen. The screen worked, however it was completely cracked and there was a black bleed mark on the LCD. I ordered a screen and began replacing it. After replacing the screen and hooking everything back up to the logic board I got a black screen. I absolutely made sure to disconnect the battery before ever touching any other part of the phone. I have also tried connecting it to iTunes and got as far as it asking for the passcode which I cannot enter as the screen does not work. Now here’s where it gets hairy and I’m stuck, after looking through the various other similar questions I attempted to test if thew screen was bad by replacing the severely cracked screen, which I knew worked. After taking all the assembly parts off the new screen and putting them back on and trying to plug it in, I got nothing. It’s still being recognized by iTunes, but now no matter which screen I have plugged in I get a black screen. I have a sinking feeling it’s going to require board level repair (which I can’t do, yet) but I’m hoping maybe someone here can see something I can’t. If there’s something you think may help me get this problem remedied or you need more information on what all I did to it, just ask and I’ll happily provide more info. Thanks everyone.
if you did not disconnect the battery you may have damaged the back light circuit -this will require microsoldering repair to replace the filter-
Backlight filter Gone, this happens once in a blue due to static or mis connection (both 6s 6sp remains with power in the last 3 pins of the connector 3.8v, if battery stay connected and even its off) . use an anti-static wrist band wen doing 6s 6sp.
