MacBook Pro: diagnosing display and camera issues
Lines on screen, a flickering image, a camera or light sensor that stops responding: the checks to run before suspecting a faulty part.
Display and screen
Physical damage (cracks, liquid exposure), a faulty display or logic board, a pinched internal cable, or dust can all cause display issues. Cracks typically produce vertical or horizontal lines or bands. First moves: remove any case or screen protector, check for signs of liquid, clean the display with a soft, slightly damp cloth, set brightness to maximum to reveal any hidden defect, and make sure you're not exceeding the supported number of external displays.
Camera and ambient light sensor
A blocked or dirty sensor, a loose or damaged camera cable, or a faulty logic board are the most likely causes. The ambient light sensor sits near the camera at the top of the screen — make sure it isn't covered by a case or screen protector. Covering the sensor lets you check whether keyboard backlight brightness reacts accordingly; opening and closing the display several times helps spot a pinched cable.
If the basic checks aren't enough
The next step is running a full diagnostic, then, if needed, opening the device for inspection or replacing the display or logic board.
