Gen 6 - Will turn on when connected to power but when I remove the power it turns off and won't turn back on

Hi,

My ipod nano generation 6 has started playing up - if it's connected to the power it'll work totally fine, I've made sure it is fully charged and then when I take it off the power it instantly turns off and won't turn back on again. I've tried holding the power button for ages, I know it's fully charged, so I really don't know what to do with it anymore.

Does anyone have any ideas?

Thanks