Hey there Kev,
It sounds like you are unable to charge your iPod but it will play when connected to power. I recommend these steps from the article named:
iPod won't turn on
If iPod still does not turn on or appears to be "frozen" you may need to reset it. When you reset iPod all your songs and files are saved. Some customized settings may be lost.
Let the iPod battery drain
In rare cases, iPod might get into a state in which it needs to be drained completely before it can be reset. If iPod didn't turn on after you reset it, follow these steps:
- Disconnect iPod from all power sources and leave it disconnected for about 24 hours.
- Reconnect iPod to the Apple iPod Power Adapter or computer and reset it.
- Make sure iPod is the only device in your FireWire or USB chain. Disconnect everything but the mouse, keyboard, and your iPod, then see if it will turn on.
- Make sure you are using the FireWire or USB cable that came with your iPod, and that the cable is in good condition.
- Try connecting iPod to the built-in port of a different computer to see if that works. Note: If using a portable computer, make sure it is plugged in to a power source and that the lid or display is open. If the lid is closed the computer may go into either standby, sleep, or hibernation mode and iPod will not charge properly.
If you still can't turn iPod on after performing these steps, it may need to be repaired. You can arrange for repair at the iPod Service Website.
Thank you for using Apple Support Communities.
All the very best,