ColorReader Pro – Press the black button on the side of the device. The indicator light found on the LCD panel will turn green when on (and fully charged) in addition to a message telling you the device is ready.
ColorReader – Press the small black button by the USB port. The indicator light next to it will turn green when the device is turned on and fully charged.
ColorReader EZ – Press the button on the front of the device. The button will turn green when on.