How to fix the magnet sensor?

The sensor is called Hall Sensor. You should validate if the lid magnet and sensor is working before you go down this path. You’ll need a rare earth magnet and a steel paper clip. Take the paper clip and slide it along the face the the display bezel on the side some where along it you should feel the tug of the magnet take not of this location carefully folding down the display so the paper clip is near the case transfer the location mark to the uppercase. Now that you know the location the sensor needs to be with the system running slide the magnet across the uppercase as you do the screen should wink out and wink back on once you’ve pasted the location. If the location is off then someone who replaced the display placed the magnet in the wrong location or the display is the wrong one for this system. If the display does not go off then the hall sensor needs replacing. The sensor is well hidden!