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I've checked everything you have mentioned about twice pulsing in LogiWiki, no described causes found on my board. But something interesting happened: I decided to reflow the SMC, just in case. After that board started, I had two short fan spins, then nothing, but CPU VCORE was present all the...

Everything can happen with electronics, but in this case it's hard for me to believe that headphones have killed CPU. Ok, PCH is related to audio, but anyway if it would be CPU/PCH they would die permanently. Customer claims that computer has started after that but shut down while loading...

CPU_VCCST_PWRGD is pulsing to ~1v, PLT_RESET_L is pulsing to ~3,3v it pulses only twice, and later nothing happens. SPI resistors are ok.

I do, I haven't connected I/O flat cable.

Yes, board is out of case, everything disconnected except DC board

I'm working on 820-00165 which as customer says has died after plugging headphones to the jack. He turned it on after that, but computer went off while loading system. Board is perfectly clean, no corrosion, no liquid, no burnt components. After plugging charger in, there is green and orange...

It behaves the same with internal LCD disconnected. With only keyboard connected, it triest to start, but shuts down after 5 seconds, with only trackpad connected it starts and boots normally, with both connected it starts, loads system halfway and restarts.

You are right, it should be like this, but in this case, when I leave only keyboard (and LCD) connected to board it doesn't start. I mean - on the amp meter I can see, that board is trying to start, it takes 0,8A for 5 seconds then it drops to 0,05A and it loops. If I disconnect keyboard - board...

No, it doesn't start at all. When I connect tracpad flex, it shows Apple logo and loads halfway, then shuts down.

@2informaticos, in meanwhile got the same mac model for repair with another issue and used occasion to swap the boards. This keboard with other board works fine. I put the board to another topcase with fully working keyboard and keyboard doesn't work. So the problemis related to mainboard itself..

I would also inspect trackpad, trackpad flex, J4800, I/O flex and J9500 for corrosion.

I started isolating pins in J4500 with capton tape and discovered, that when i isolate upper row of pins in connector, board boots fine. Then I isolated left/right half of pins, it turned out, that with right side of upper pins isolated board boots fine. I started isolating each pin separately...

I'm sure they have replaced complete topcase. Only things they left are motherboard, Touch ID, display and screws. They have replaced topcase under keyboard replacement program, but as computer already doesn't have warranty, they left it like that and said, that motherboard needs to be replaced...

Exactly, it was restarting all the time during boot. But today for example in most cases board doesn’t even try to start with keyboard connected.

@2informaticos, do you have any ideas?

Where was the area liquid got on? Do you have other S5 rails present? Check the diode reading on PP5V_S5. Also if you have S5_PWR_EN. Are PP3V3_S5/SUS present? SMC_PM_G2_EN present? If you have PP3V42_G3H present then you should have green light on charger, unless J9500 or I/O cable are...

Thanks, it's clear now ;)

Funny thing is, that first I have flashed bios as it was, without any modification. I've connected only display and as it booted fine I decided to change S/N before going on with assembling and further testing. I haven't tested keyboard then. Anyway, I managed to figure it out. It can be a...

Reflashing EFI did the trick, computer starts now, loads system. Now I have 2 other problems: - I've changed the fsys region in bios you sent me with the original bios fsys (I've copied everything from this region) but S/N doesn't show up in "this mac" info, also when I want to run diagnostics...

Not yet, I don’t actually have known good one (only original and one with came with donor board). I will need to search for it, or if you have it and will be so kind, I will be grateful for sharing it with me.