TV Philips 42pfl6057h/12 blink 2 times and not turn on

Good evening, I have a TV as described that won't turn on and the led, after about 5 minutes that it's powered on, flashes twice endlessly.

I opened the back panel and measured if the voltages feeding the motherboard were present.

So at the output I have 3.3 and 12 volts and the standby voltage goes to 3.3 then to zero every time the switcing starts because when the TV is on I hear a very faint hissing of the switcing transformer and the processor touching it gets warm, after a while it cools down, the very faint hissing is heard again, the processor gets warm again, everything continues until the led starts blinking.
The voltage measurements I made on cn4 of the attached schematic.

Do you think the fault may be in the power supply or the mainboard ?