MacBook Pro 14″ (M4, 2024) boots fine on battery but instantly powers off when any charger is plugged in

[kaltisami]

Model & history

• MacBook Pro 14″, late 2024 (M4, base model)
• Tea spill on keyboard ~4 months ago. Local shop did a cleaning—no parts replaced. Machine has worked perfectly since.
• Battery still healthy; macOS Sequoia.

Current symptoms





If I power up on battery alone, the Mac runs normally (until it dies from low battery).
As it's low battery, when I power up I get a message that displays the "runs on reserve battery life" and the macOS first shows the yellow-triangle “The version of macOS on the selected disk needs to be re-installed” screen. When I click Recovery → Reboot the macOS from Recovery, the Mac runs normally .



The moment I attach any external power—Apple 140 W brick + MagSafe 3, known-good 96 W brick over USB-C, or USB-C on the opposite side—the MagSafe LED blinks amber for ≈1 s and the whole laptop shuts off. Same behaviour on both USB-C ports.



Reconnecting the charger while the Mac is off causes a brief blink, then nothing. Unplugging the charger lets me boot again on remaining battery.



Tried three different chargers and two MagSafe 3 cables; cleaned all ports with 99 % IPA; let it dry 24 h—no change.

What I’ve ruled out / measured
• Charger and cable (swapped).
• MagSafe DC-in board (visual inspection—looks clean, no charred pins).
• Battery fuse appears intact (machine boots on battery).
• Liquid-detection lock doesn’t match the hard power-off I’m seeing.

Suspicions from research
• Faulty RAA489900/RAA489901 charger IC (U7200) or shorted PPBUS bulk cap.
• Less likely but possible: both CD3219/3220 USB-C PD controllers or the ideal-diode MOSFET pair.
• Repeated hard shut-offs are probably what corrupted the Signed System Volume and trigger the yellow-triangle screen.


Goal
Figure out the issue and whether a U7200 re-chip (or cap swap) is worth attempting if that's the cause.

Thanks in advance for any schematics, voltage points, or hard-earned wisdom you can share!

 

[dmccloud]

Chances are that the tea spill is causing the issues you are describing. Even if a local shop "cleaned" the system after the spill, in no way would that prevent either short-term or long-term damage to the internal components. The damage could be on the other side of the logic board or internal to components on the logic board, so you might not be able to see it easily.

Attempting to do component-level repairs on a system known to have been exposed to liquids is a fool's errand IMO, largely because fixing one component might reveal additional items on the logic board which were also damaged.

 

[kaltisami]

Chances are that the tea spill is causing the issues you are describing. Even if a local shop "cleaned" the system after the spill, in no way would that prevent either short-term or long-term damage to the internal components. The damage could be on the other side of the logic board or internal to components on the logic board, so you might not be able to see it easily.

Attempting to do component-level repairs on a system known to have been exposed to liquids is a fool's errand IMO, largely because fixing one component might reveal additional items on the logic board which were also damaged.

Thank you for your answer, I apreciate it.
But then, what should I do?

 

[adrianlondon]

It's under a year old. You could try taking it to an Apple store and letting them take a look.

I believe they don't charge to check things, so if they come back and say (definitively) that it's due to the liquid damage, ask them to quote you to repair. The quote should detail what part(s) they will replace.

 

[Teletypewriter]

I have charged my M4 base laptop with my Apple iPad Pro 20w charger in a pinch. It takes forever, but it will charge your laptop at a slower rate.

 

[Fishrrman]

Looks like you're either going to have to:
a. pay for a repair
or
b. buy something new or refurbished (if you want "full operation" back)
or
c. keep using it "as it is", with its current limitations.

Like this guy says:

 

[FreakinEurekan]

Looks like you're either going to have to:
a. pay for a repair
or
b. buy something new or refurbished (if you want "full operation" back)
or
c. keep using it "as it is", with its current limitations.

... and ensure your backup strategy is up to date, ESPECIALLY if you decide on option "C" 😬