Try to reset the board by removing the batteries for several seconds. Then try to turn it on. If that doesn't work, I suggest contacting Emory at
[email protected] and ask for further help. It might be an electronic failure which is covered by warranty.
Did you unplug the saber before clicking "Disconnect" in the launcher? If so, that could be the cause for the error message. Always disconnect boards (no matter if it's Obsidian, Emerald or Diamond) from the launcher first before physically disconnecting the saber!