Ask DELL Inspiron 24 model 7459, motherboard IMPSL-PO rev A0 - schematics

[TadejMihelic]

Hello!

I have a DELL Inspiron 24 on my bench that had a "no power" issue. I replaced 2 mosfets that were shorted (first one and on the back one 508SG).
The main power rail is no longer shorted, but the computer won't turn on. When I press the power button, it turns on for a second (and starts the fan for a moment) and then immediately turns off.
What could be the problem?
Does anyone have schematics (and boardview) for this motherboard?

Thank you!

 

[ThienBui]

current no have Schematics model this

 

[TadejMihelic]

current no have Schematics model this

I re-flash the BIOS and there is no change :/ I check voltage on the coils and I have all lines... hmm....

 

[TadejMihelic]

current no have Schematics model this

Besides the basic bios chip (winbond) there are three other ICs on the back side of the board that I suspect are bios?
MXIC 25L512E, MXIC25L4006E and MXIC 25L1006E.

What should be on these? Can it be reflashed?

 

[ThienBui]

Besides the basic bios chip (winbond) there are three other ICs on the back side of the board that I suspect are bios?
MXIC 25L512E, MXIC25L4006E and MXIC 25L1006E.

What should be on these? Can it be reflashed?

only Programming one main bios

 

[TadejMihelic]

only Programming one main bios

I suspect it's a CPU issue. :/

One of the FDPC5018SG on VCORE was faulty, as a result the input mosfet on the main power rail was also faulty. I replaced both.
There is now 19V present on main power rail and also 5V, 3.3V, 1V and 0.8V on coils on entire board, but nothing on VCORE coils (on dual mosfets on vcore the 19V on source is present, on drain is nothing).
And there is also VERY LOW resistance on vcore coils (0.8 ohm), what could be shorted cpu?
I think that the usual low resistance on the VCORE is around 8 ohm (and not 0.8 ohm). Am I wrong?

TNX!