I. for X401 and X506
6). If it suggest ok, reboot the phone.
Pictures guide (special thanks for supporting from Isham Mohamed Iqbal)
Setting –> Display –> select Proximity Sensor Cablibration –> OK
Setting –> Display –> select Als_ps calibration –> cover the two black points between front camera and speaker with finger (the distance between finger and the points should be about 5mm-15mm) –>select calibrate (keep covering the two black points) –> the blue circle become green –> OK