You have asked a great question! To get to the root cause of the issue there are a few questions I would like to ask. Have you tried a different charger with the device? If so, do you still get the same connecting and disconnecting sounds? When it makes these sounds does it show on the battery at the top of the device that it is connecting and disconnecting? Have you tried a soft reset of the device? Hold down the power and home button at the same time until the phone restarts.
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