Powers on , Black Screen

Hi guys , I am repairing an IPhone 5 for a customer who recently had the screen replaced by a friend but since then the phone hasn't worked so she brought it to me. Instially it would not power on, no signs of life.

Issues i fixed - Power cable was torn so i replaced , missing many screws so i replaced with proper screws, battery was bad so replaced the battery as well.

Now the phone is recognized by itunes but the screen is black . the backlight is lighting up but no image.

Also water damage sensors have changed color but no signs of corrosion on visual parts of the board .

Screen works as i have tested it separately outside the damaged phone.