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I'm trying to revive a MacBook Air 2017 that suffered a liquid spill (diet Crystal Light on the keyboard). After a week of drying, open, in an aggressively dehumidified room, it started up and behaved normally for a week or so, but then failed to start up. Now it won't boot at all or respond in any way.
Laptop: 13" MacBook Air MQD32LL/A (1.8GHz Core i5, 8GB)
Logic board: 820-00165-A
This question differs from No sound (speakers/jack) + microphone's dead after spilling water. I am asking whether the described symptoms isolate the problem to the logic board as opposed to other parts, which is not asked or answered there. Repair/replacement of the logic board is relatively expensive, so it would be useful for people in this or similar situations to be able to evaluate the level of certainty that the logic board is the locus of the problem. Although I reviewed numerous related questions including the above, I haven't seen any thorough treatments of this question.
- I don't see any sign of liquid remnants or corrosion on any internal components, but the moisture detector under the display data cable connector was activated.
- After the charger hasn't been connected for 10 minutes or so, when connected its diode will flash green for an instant, once. Other than that, the diode will not light, even dimly. Tested with two known-good Apple Magsafe chargers; same results.
- But with the battery out and the I/O ribbon disconnected, when I connect the charger its diode lights up green (or occasionally amber) for a minute or so then fades slowly to dark. (Interesting: In order to repeat this sequence and get the diode to light again, it seems the charger has to be connected to a different, known-good computer, just for a second, as if it needs to reset itself.)
- SMC reset: No response and no change.
- Jumping the power pads: No response, even with keyboard/trackpad ribbon disconnected. Tested with battery and charger, battery only, and charger only; also with charger only and I/O ribbon disconnected.
- Tested with a second known-good battery: No change
- Replaced top case: No change
- Replaced I/O board and I/O ribbon connector: No change
I don't know whether the Crystal Light got to the logic board or if this problem could be caused a fault in a cheaper part, say the I/O board — and maybe I got a second faulty I/O board.
The question, more precisely: Do the symptoms described indicate that the problem is almost certainly in the logic board, or almost certainly somewhere else, or is it inconclusive?