Check the circuit breakers and main breaker to ensure the venues power is in fact on and then check the rear of the cabinets to see if there are indicators lights on .
Indicator lights on means there is power but no video signal and you need to –
• Check the AV source connectivity at the Led processor
• Check the data cables at the LED processor OUTPUT and the Screen lead in INPUT
• Ensure the Led processor has the correct input selected
• Ensure the AV source is using a resolution that the screen processor can support
• Check LED processor input and output resolution settings
• Check LED processor scaling settings