Macbook A2338 M2 (820-02773) not turning on

[szape]

Hello!

I have a Macbook Pro M2 2022 which does not turn on. Both ports have the same behaviour: 5v, then 20v then meter turns off and restarts.

DFU mode works but trying to recover in Apple Configurator fails (Unexpected device state 'DFU' expected 'RestoreOS' (Probably forced into DFU mode externally)). Apple logo comes on, after 20-30 seconds apple logo disappears but backlight stays on for a minute and then switches off completely at the restore process.

Charging works in DFU mode.

PPBUS_AON is fluctuating between 12V-12.4V (diode mode reads 0.440 instead of 0.496)
3V8_AON is present, 3.8V stable
P3V8AON_VSW1 is fluctuating between 3.4V-3.9V

Any suggestions? Thank you.

[mon2]

Remove all power. Disconnect the battery. Meter in resistance mode. Measure the resistance to ground of each and every inductor. Hunting for a lower than normal resistance on the inductor which often will indicate a shorted part on this power rail.

[szape]

Thanks for the suggestion. Logic board is already removed from chassis, will measure inductors and i'll come back with the results. What resistace is lower than normal? I have a boardview but only see diode mode readings on it.

[szape]

I'm measuring the coils but get strange readings. Sometimes megaohms, sometimes kiloohms at the same inductor at different times, tried with 2 multimeters but same results. What am i doing wrong?

When logic board connected to charger LF800 shows steady 110kOhms, L5230, L5800, L5820, L5840 and LC260 switches between 0 ohms and O.L., LP800 is going insane.

[mon2]

Low voltage rails will be low resistance by design. Post any suspects and we can review.

That is ok on your measurements - may be a slight charge onboard. We are more concerned about low resistance like ohms and the meter remaining in that range. No power during any of these tests.

[szape]

I measured all bigger inductors without power. The lowest ones are about 0.570kOhms (L5800, L5820, L5840). But i can't measure inductors around U7700 and U8100 they are too tiny.

I've found that under thermal camera L5800 gets hot. And i've inspected the board under microscope, Q5840 might have a crack on the top but not completely sure. might be a scratch, i can see only at the top but not at the sides. I can upload pictures if needed.

And i must tell you that this is my own macbook and this is my first repair attempt (previously repaired ipads, tablets and consoles which had damaged ports or visible faulty capacitors etc.) I have thermal camera, hot air station, microscope and micro soldering station.

[szape]

Meantime I measured PP2V5_AWAKE_NAND because of the Apple Configurator restore error (4014) but it seems fine. 2.58V, looping.

And one more thing to add: touchpad does not click at all even when apple logo showing at restore process but keyboard works because i can trigger DFU mode.

[szape]

I'm stuck at this point. Measured the board further, 5V is present and steady, can't find any short. Maybe i need a better thermal camera? My current one is Seek Thermal Compact with macro lens, the refresh rate is only 9Hz...

[mon2]

The refresh rate of 9hz is a DOD (USA) 'enforcement'. We are also stuck at this crappy rate. The mfrs laughed at us when we met them in Asia and repeated they are at 25hz overseas with off-the-street hardware. Ironically, the 25hz units are also being sold on Amazon. The quality improves each year but Seek is a good brand and an USA company. I have some names of add-on thermal cameras for phones out of China. Believe ~$150 USD for their android camera using Chinese thermal sensors. Aside from all this, do not believe it is the fault of the camera on your reviews. The camera you have should be fine.

[szape]

Thanks for your detailed information. Then what's next? I'm looking at the schematic to hunt for the secondary power supplies, watched a ton of Louis Rossmann's tutorials but since i'm a beginner i'm stuck but i won't give up this easy.

Inspected the board again under microscope and found a tiny solder ball between L8290 and L8291, around L8271 and found one more somewhere near but don't know its exact location. Removed them all, but nothing changed.