Cracked Screen
If the glass/LCD is cracked, has a distorted image, no image, or is malfunctioning....
Battery problem
If your device is not charging, not holding a charge, or dying faster than it should....
Charging port problem
If you power down the device and it turns right back on, or you are having trouble connecting the device to a computer or charger....
Ear speaker
If you hear the fuzzy/cracking sound, if sound fades in and out, or if there is no sound at all....