I've just got to the point of first power on to tune the stepper drivers but I have nothing on the LCD display. Swapped the ribbon cables as suggested and still nothing. Troubleshooting guide is "coming soon" so now am at a dead halt. The two 24 DC supplies have power and the electronics cover fan is spinning so power is getting to the Rumba. Any suggestions because clearly something is very wrong, I cannot see any mistakes on the wiring but with no LEDs and no LCD screen I am in the blind.