Replace BASEBAND power ic PM9645 located near audio ic at the backside of motherboard. If no repair history of phone then ur phone willb ok by PM9645 else u have to reball Baseband CPU. It can be done by professional only
iPhone 7 home key flex has been broken while changing screen, go to any professional shop it is easy to repair this problem as only a small secondary flex in home key damaged not primary big flex.
Serial no is not there that means someone has repaired its NAND ic. If serial no present but no imei then it is issue of Baseband bt in ur case serial no not present but imei is there it is clear issue of NAND Data.
Its screw hole damage case as u hv put a wrong screw on left side of display connector shield. Thats why display and backlight is not working. u hv to fix it by any professional repair
This component is not related to backlight section It is PN5.7 line which is aroung OL in diode mode and it generate by chestnut ic u r getting ur display image right if yes no issue of this line. Check anode line on display connector buddy.
