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A2681 820-02536 liquid damage boot loop

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Sam A

New member
Most of corrosion was present around USB-C controllers and charge controllers (U500, UF400, UF500, UF000, UF100), and capacitor block near UF900, UF930, and UF960.
Only found a couple legs/pads corroded enough to cause a possible connection problem (UF960, UF900). Was able to clean them up and re-solder.

After corrosion cleanup, I get Apple logo, boot progress bar goes about half way, then powers off and repeats.

Powers on and starts to boot as soon as USB voltmeter negotiates 20v. Amp reading jumps around below .2 while booting but powers off as soon as amp reading jumps (or tries to jump) above .3A. At this point CPU becomes momentarily warm, but not before this. Audible "click" from board when it powers off, and voltmeter shows 5v 0a.
Most of the time will click a few times while at 5v, then negotiates 20v and tries to boot again.

Same symptoms on only battery power or using either USB-C port or magsafe for power.

Same symptoms with logic board out and only connected to power or assembled into system.

In DFU mode, stays powered on, voltmeter stays at 5v, but can't perform any operations--says "system is not booted".

Only need data.
 
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Sam A

New member
No. On this M2 Mac, target mode is accessible from Startup Options, which is accessed by holding down the power button from a powered-off condition. When I hold down the power button, I get the message "Loading Startup Options", but it never reaches Startup Options before powering off and attempting to boot again.
 
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Sam A

New member
I do not currently have a Mac available that supports Sonoma--which apparently is required for DFU blaster. I will have one at the beginning of next week. Can you think of anything else I can look at in the mean time?
 
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Sam A

New member
No luck with DFU blaster. Can enter DFU mode but logic board just clicks and voltmeter stays at 5v when I try the "restart to recover" option.

I see in my original post that I forgot to mention that there was corrosion around UC830, UC840, and UC850. The contacts still looked bad enough after cleaning that I replaced all 3 with no change in symptoms.
 
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Sam A

New member
Any action in Configurator (notably selecting "Backup") gives the error: "Configurator could not perform the requested action because the device is not booted".
 
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Sam A

New member
PP3V3_S2 value rises rapidly, when it hits ~2 goes wide open
PP1V8_AON 1.25
PP5V_S2 1.7
PPBUS_AON 2.005
PP3V8_AON 1.43
PP1V8_S2 .98
PP1V8_S2SW 1.4
PP5V_S2SW_IPD 1.23
PP3V3_S2SW_IPD 1.24
 
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