Acer Aspire 5749 DA0ZRLMB6D0 does not turn on

Hi everyone! I have an Acer Aspire 5749 with a DA0ZRLMB6D0 motherboard which does not turn on or do anything.
The consumption is 0A and when pressing the power button it only goes up to 0.020A for a few seconds.
I have measured the resistance with respect to ground of the main coils:
PL11 ... 18Ω
PL14 ... 113Ω
PL10 ... 260Ω
PL6 & PL7 ... 6,5Ω
PL8 ... 21Ω
PL9 ... 6,5Ω

+3VCPU and +5VCPU are present.
+15V is present but with 12.88V. The value is a bit low and I don't know if it is within the normal range
On the power button the 3V is present and when pressing the button it drops to 0V.

On the KBC I have made the following measurements:
Pin 26 ... 0V (S5_ON)
Pin 75v...0V (RSMRST#_UR)
Pin 76 ... 3,3V (+3VPCU_EC)
Pin 91 .... 0V (DNBSWON#)
Pin 95 ... 3,3V (NBSWON#) When you press the power button it drops to 0V
Pin 64 ... 3,3V (ACIN)

Any help?

Who or how are the 15V generated? I don't understand the diagram.

The 15v are generated by the voltage doubler formed by PD7, PD6, PC150, PC146

Machine ha scritto:The 15v are generated by the voltage doubler formed by PD7, PD6, PC150, PC146

Thank you so much

In that case, I interpret 12.8V as a low value, right?
Therefore, there must be some bad component in that area
Is this correct?

No, even 12.6V are sufficient to make the mosfets conductive.

Can someone help me and guide me? I don't know where to continue I still don't know how to interpret some values.

- Measure the voltages to ground on pins 44, 93, 102 of KBC chip.

- Measure the voltage to ground on pin 91 of KBC chip in the following cases:
a) Power button released.
b) Power button pressed.

Now disconnect the power supply, wait about two minutes, reconnect the power supply and perform the following measurements:

- Measure the voltages to ground on pins 7, 21, 26, 73, 75, 82, 117 of KBC chip in the following cases:
c) Before pressing to the power button (machine turned off).
d) After pressing to the power button (for a short time, when the power consumption is 20mA). You will need to turn on the machine several times to perform all the measurements.

matic ha scritto:Measure the voltages to ground on pins 44, 93, 102 of KBC chip.

Pin 44 ... 1,8V
Pin 93 ... 3,3V
Pin 102 ... 3,3V

matic ha scritto:- Measure the voltage to ground on pin 91 of KBC chip in the following cases:
a) Power button released.
b) Power button pressed.

a) .... 0V

b) .... If I press the button the voltage is 1.63V and if I hold the button down, the value is 1V for a second and then drops to 0V, until I release the button and then it goes back up to 1.63V.

matic ha scritto: Measure the voltages to ground on pins 7, 21, 26, 73, 75, 82, 117 of KBC chip in the following cases:
c) Before pressing to the power button (machine turned off).
d) After pressing to the power button (for a short time, when the power consumption is 20mA). You will need to turn on the machine several times to perform all the measurements.

c) .... On all pins the value is 0V

d) Pin 7 ... 0,01V
Pin 21 ... 0,22V
Pin 26 ... 0,02V
Pin 73 ... 0,01V
Pin 75 ... When pressed, for one second 3.14V and then 3.07V
Pin 82, 117 ... 0V

Measure the voltages on pin 4 of U4.

Machine ha scritto:Measure the voltages on pin 4 of U4.

The value is 0V, and when pressing the power button 0.61V

Measure the voltages on pins 91, 95 of KBC.

Pin 91 .... 0V
Pin 95 .... 3,3V When I press the power button it drops to 0V

You have a problem with the PCH, you can try a reflow but for a lasting repair you must replace the PCH.

First of all, thank you very much for your help.
The option of changing the PCH is not viable because the rework machine is broken.
In that case, the only option left to me is to change the motherboard, but I have a question. This motherboard has an i3 processor. If I buy a motherboard that had a Celeron processor, or an i5-i7, when I put in the i3 CPU of this broken motherboard, do I have to update the BIOS or ME region, or is it updated only when I put in the CPU?

Sometimes I get confused and ask logical questions... Maybe it's my age!
In the end, I asked for a motherboard, it was changed and the computer continued to work.
As always, thanks!