Attempt to power on the device while it is connected to the adapter/charger.
Ensure that an Apple approved battery charger is being used.
Ensure the device is properly connected to a valid power source (preferably an AC adapter and not a car charger).
USB cable-to-computer charging shouldn't be used for testing lack of power.
Verify that the device and charger display the appropriate charging/LED indicator.
If the battery level is extremely low, the display may remain blank for up to 5 minutes before a low battery image appears.
If the device displays a low battery image, it may take up to 20 minutes before the device powers up.
A battery that is completely drained should be charged for a minimum of 15-20 minutes.
Attempt to power on the device using an alternate charger, if available (Apple approved equipment is preferable).
Ensure the charging port contains no water damage or corrosion.
Water damage is not covered under warranty.
Check the charging port for bent or broken pins.
Physical damage is not covered under warranty.