This happens when the device shuts down due to the battery being flat, completely dead, and then either not being recharged for some time, or attempting to power on the device before recharging it. To get the device to turn on, insert a pin needled size object into the pinhole and hold down the reset button for four seconds. Device should now turn on by holding down power button per usual. If the device still does not turn on you may find other possible errors and solutions on the troubleshooting page located here.