Acer Predator Helios 300 - will not power up if battery is CONNECTED

[survivalbloke]

This was a no power initially. Thanks to your help, I discovered it was the first mosfet, so I replaced. Now, the device will power up only if the battery is NOT connected. As soon as I connect the battery, it shuts off. If I connected the battery while the device is off, it simply will not respond to the power button. I replaced the battery, and while I suppose the new battery could be faulty, I'm assuming it is not. I'm having the same behavior with the new battery. I measure .2v at the charging coil. Manually applying power to the + and - at the battery header, there is no charging happening. Thanks in advance!

Acer Predator Helios 300
Model PH315-54-748Y
SN: NHQC5AA0011440BA443400
Board GH51G LA-L181P Rev 1B

[mon2]

Review the 2nd mosfet.

[survivalbloke]

Review the 2nd mosfet.

2nd mosfet measures 19.8v on source and drain, 25.9v on gate.

[mon2]

Check the battery mosfet. Suggest to remove all power and check the resistance across the source / gate / drain pins.

[survivalbloke]

Check the battery mosfet. Suggest to remove all power and check the resistance across the source / gate / drain pins.

There are three mosfets beside the BQ chip.

PQB6: was first readin 6.5k source and drain, 125k source and gate, but now, somehow it is reading 9M source and drain, and I checked a third time and getting 7M source and drain.
PQB5: 21M source and drain, 105k source and gate
PQB2: 21M source and drain, 13M source and gate

Question about mosfets... If I have my meter in diode mode, with Red - Source and Black-Drain, I should get ~0.5v, but if I reverse that, I should get OL, correct? If that's the case, then my first DCin Mosfet is working correctly, but the second one, along with all three of the mosfets near the BQ chip show 0.45 with red on source and black on drain, but if I reverse those, I get 1.5v and it steadily increases. If I'm understanding, that is not normal, at least for N channel mosfet, correct?

[Sephir0th]

These measurements aren't conclusion when done inside of the circuit. There are always other components which interfere. This means when you want to make absolutely sure, you need to remove the Mosfets in questiin and measure them out of circuits. In-Circuit you are normally good to go as long as a Mosfet (in the DC-IN circuit) measure above 1 KiloOhms in any direction.

But generally spoken, 25V at the Mosfets gate are already enough to tell they are good.

Does battery power reach the Main power rail when connected only (without charger)?