Method 1, the motherboard power supply is normal (5V or 3.3V, some is a single 12V), remote control or button power on or off indicator does not change, generally the motherboard failure. If the motherboard is powered by a single 12V, use Method 1, which is basically not misjudged.
Method 2, first check whether the power supply of each power supply board is short-circuited, and then disconnect the motherboard, add 5v or 3.3V to the power board boot port (PW, PWR, PS-ON, STB), and backlight control on the power board or backlight board. Port (backlight adjustment A/P DIM=PWM=ADJ=OFL=I/EPWM, backlight switch BL-ON=BRI=INV-ON=BK=SW) plus 5v or 3.3V, backlight long light indicates backlight and power supply Normal, you can choose to repair or purchase the motherboard. This method is more accurate.