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. T