Proximity Sensor not working after repair

There are a number of reasons why this can happen:

• The sensor is not properly aligned. Tear down and reassembly may help fix this. Make sure the plastic bracket is properly positioned like in the original;
• The sensor cable or sensor solder joints were damaged during the transfer and now the whole front camera cable assembly needs to be replaced;
• The cable needs reseating into the connector on the board;
• The screen itself is somewhat defective and allowing too much light through. Specially for the black screens. Transfer the small white filter or try coloring a little bit the opening where the sensor sits behind the screen.