Asus x512dk rev 2.1 power on problem

[Duranitron]

When I reflash again the bios of hoaca388 the unit powers on and the unit lives!!! Hooray!! All voltage in the coil 3.3v, 5v and 6.7v indicate charging are all present. including the cpu voltage , EEPROM and GPU voltage the unit is now alive, normal screen booting to windows and log in screen until I power it off. Then the unit never goes on even when pressing the power button in the keyboard.. Voltage reading 19v main , 3.3v VCC in IT8225E-128 and EEPROM VCC 0 volt and the charging voltage 0 volt.

Try to trace the power switch button goin to the power switch IC PU8803 (APL3533AQBI-TRG) monitoring the trigger voltage in pin 3 of PU8803 while pressing the power button it measures 0V. PU8803 is the one the produces the 3VA ECO or 3VA EC to power the (U1901) IT8225E-128, There is no effect when pressing the power button. power button pin has 3.3v then goes to 0V when the button is pressed. I'm excited in tracing the circuit using the board view. it leads me to this mosfet Q2202 (UM6K1N) which is connected to the power switch button pin 2 and pin 3 PS_ON_D which is connected to the enable trigger of pin 3 of PU8803.

My question is what should I measure in the PS_ON_D when I press the power button?
is it steady 3volts to enable PU8803?
should I replace the Q2202 or should I trace it further?
thanks for your patience..

[Duranitron]

I found the culprit resistor PR8825 is not present connecting PS_ON and PS_ON_R installing a 10K resistor creates the VSUS_PWRGD signal that enables all the Power IC,
including the 1.8v (PU8401) and 0.9 volts (PU8301). Only the PU8701 is not enable though VSUS_PWRGD is present. Gonna check tomorrow if both enable signal pin 6 and 20 are present.?

[Duranitron]

PWM CONTROLLER RT8249CGQW PU8701 is not turning on because of a shorted mosfet PQ8703. The problem is when I replaced it, the new mosfet shorts again.. what seems to be the problem with that. checking the coil connected to the mosfet doesn't have any short to ground..any Idea guys.

[mcplslg123]

If you got display after bios flash, there is unlikely to be any shorted component on the motherboard.
If the power button is on the keyboard,that may be the culprit. Try turning on without keyboard by shorting the power switch pin on kbd connector.

[Duranitron]

Thanks for the reply. I already turned on the unit by shorting the pin 25 of the keyboard connector.. only the 5v and 3v coil voltage is not present. There is no short in the 3.3v rail but I measure 1 ohm resistance from coil to ground. I remove the soldered joint that connect the 3.3v rail to the 3.3v coil to isolate the 3.3v supply to the circuit. The 3.3v power supply is rated at about 10 to 30A , I think the problem is in the 3.3v supply. Removed the shorted mosfet PQ8703 and replaced it with new again.. power it up.. then the mosfet PQ8702 shorts but not he PQ8703.. Investigating if this mosfet really shorts or just in the on state. Create a mosfet circuit to reset the mosfet by supplying the mosfet with negative and positive feedback on its gate to turn it off with No avail the mosfets is shorted. All pins are shorted. Any Idea what causes this?