Plug the 9 volts mains power into the pedal first of all  Then plug the USB cable in after around 5 seconds or once the pedal has fully powered.

If the 9 volts mains power to the unit fails, then before re powering, unplug the USB cable.  Wait 5 seconds and then plug the power back in again followed by the USB cable 5 seconds later.

If the USB is plugged in before the power then there will be a greater chance that the pedal will not be recognised by the TonePrint Editor.