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"How to reset an iPod nano (6th generation)
Press and hold the Sleep/Wake button and Volume Down button simultaneously for at least eight seconds or until the Apple logo appears. You may need to repeat this step.
If the above step did not work, try connecting iPod to a power adapter and plug the power adapter into an electrical outlet, or connect iPod to your computer. Make sure the computer is turned on and isn't set to go to sleep. Try resetting the iPod while it is connected to power."
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