usually if there's a problem other than the power supply, leds on monitors and tvs flash a code sequence. if it's just flashing, most likely it's the power supply. 90% of the time it's bad electrolytic caps, about 7% of the time it's a shorted diode or regulator. the other 3% of the time it's something else shorted. if it's flashing a code sequence, the code sequence is an indication of what is wrong, such as the CPU or backlight inverter, etc...