According to consumer forums, you have to place the device in recovery mode and restore it:
- Disconnect the USB cable from the device, but leave the other end of the cable connected to your computer's USB port.
- Turn off the device: Press and hold the Sleep/Wake button for a few seconds until the red slider appears, then slide the slider. Wait for the device to shut down.
- While pressing and holding the Home button, reconnect the USB cable to the device. The device should turn on.
- Continue holding the Home button until you see the Connect to iTunes screen.
- iTunes will alert you that it has detected a device in recovery mode. Click OK, and then restore the device.
There's nothing worse than being in the middle of your favorite song, the most exciting part of a movie, or at a key point in a game and have your iPod touch run out of battery. Luckily, there are ways to save lots of battery life and squeeze every last minute of fun out of your touch.