I just took my Neato XV-11 apart to clean hair off the brush motor shaft. After I put it back together, I tested it and it ran fine. Later I tried to start it and the orange light came on solid, with no LED message. Removed batteries, and checked, they are fully charged.
It sounds like there may be damage to the LCD cable. When you took the robot apart, did you take care to lift the top cover slightly to disconnect the ribbon cable? If not, the pulling of the top cover may have damaged the connections of the ribbon cable on the LCD board.
Can you please take the robot apart again and verify the ribbon cable connection?