If the your device has a cracked/smashed/damaged screen then you will need a screen replacement.
If you can't hear the person on the other end of the phone or if the sound is distorted.
Microphone Repair for when others can't hear you or complain that you sound quiet or muffled.
Repair or replacement of camera module if your camera is not working or the pictures are blurred.
Headphone Jack Repair/ Replacement for when your headphones stop working or have no sound from one ear or something is jammed in the port.