Chosen Solution
After replacing the screen the backlight acts strange. After starting the phone, the screen switches on for a short period of time. Touching brightness settings causes the backlight to fail. The image is still on, but there is no backlight. Is this the case of a blown fuse or shorted circuit? Could this be the case of improper connection of cables? I have tried 3 different screens, only the latter one comes on for a short time, other 2 do not even light up. At startup, I can never see the apple logo, it’s only after the phone is on, I might get lucky to see if the backlight switches on after pressing the unlock button I caught the anomaly on camera
If you are sure the screens are not faulty I would inspect the LCD connector on the logic board. If it was a blown filter or short it would never come on. Check the pins on the connector and the components I have marked in red. Make sure the pins on the connector are not pushed in and that the other components I have marked are not lose.
