How do I check for feed-in power problems?

Overview Feed-in power issues — where the main AC supply or primary power input to the LED screen system is unstable, insufficient, or interrupted — are a common root cause of display faults. Symptoms Entire screen does not power on. All status lights are off across the screen, power supplies, and control cards. Intermittent or random shutdowns of the whole display. Visible flicker or dimming across all modules simultaneously. Power supply status LEDs flicker, blink, or cycle off/on. Troubleshoo