MacBook powers off about 1 second into boot

Hi, I'm trying to see if I can narrow the problem down any further; I suspect a logic board or heat sensor.

My laptop was running on battery, I left the room, and when I came back a while later it seemed to have gone to sleep. I pressed a key to wake it up and it made disk drive startup sounds but nothing else; the light on the front was still pulsing.

I figured the battery was low, so I plugged it in and the battery charged up fully according to the battery lights, but the computer still wouldn't wake up so I powered off. Now, if I try to turn it on, the fans and drives start spinning and then the whole thing just shuts down within about a second (it sounds as if you had held down the power button to shut off). There was a DVD in the drive but I couldn't even coax it into ejecting so ended up opening the drive case to remove the disc.

I'm pretty sure they replaced my main board when I brought it in for a display replacement a couple of years ago (the board qualified for replacement because of an NVIDIA GPU issue I think).

If I remove both DIMMs, I get a repeating single beep indicating no RAM — it seems content to run like this for ages. If I hold down the power button, it will stay on until the front light starts flashing rapidly, which I understand means it's looking for a firmware update, and then immediately turns off.

Other than that, I have tried:

  • resetting the NVRAM (no change)
  • resetting the SMC (no change other than faster spinning fans on the next boot attempt)
  • swapping and removing DIMMs one at a time (no change)
  • individually disconnecting each of the connectors (drives, sensors, fans, etc.) on the logic board and trying to boot; nothing of note except:
  • * I didn't disconnect the keyboard connector, since I couldn't turn the power on in that case
  • * with the the left I/O board connector off, the machine doesn't do anything
  • trying A/C only, battery only, and both (same behaviour in all cases)

Does anybody have any other suggestions to narrow the problem down or a confident sense whether it's the logic board or not? I'm a bit thrown by it's ability to sit happily beeping with no RAM in.

Thanks!

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AFAIK it's standard to beep RAM missing/failed - there's no automagic shut down for failed RAM.. but without RAM the boot process can't finish.

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Thanks. What I'm trying to narrow down is what the problem might be given that it will stay powered on with no RAM but will shut down with RAM.

I'm not convinced the problem is anything to do with the RAM, per se, particularly since the problem is exhibited with either stick in. I suppose it could be some kind of memory subsystem component, but I guess most likely is that some stage after the memory check is killing it and removing the memory simply prevents it getting that far.

Since the machine dies within about a second but only with RAM installed, that should narrow things down component-wise... Presumably it's not a heat sensor, because I expect those would kick in even without RAM installed? Can anyone confirm that?

I'm hoping someone either (a) has a thought on something else I could try to diagnose/fix or (b) can confidently say what I would need to replace.

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I don't know how much $ you want/or it's worth to spend for repairiing the box. Maybe part it out? Sounds to me like you need an entire new logic board.

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hi did you fix your MacBook? I've the same exact problem in my 2015 macbook air.

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Hook it up to an external monitor and see if it is generating a video signal.

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Thanks - have just tried. There's no video signal, but the laptop shuts off within about a second, well before the laptop screen would normally show anything anyway, and an external monitor would normally that long to detect a signal if it was there...

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On the left I/O board #820-2273 you will have three fuses. On the back side of the board 2 each on the upper side consequently one. These are called SMD fuses, F9800 and F7902. Color White. On eof them is pretty small. The best way to look for them is removing the Black feel off after you removed the four philips screws. The other fuse is located on the upperside close to one of the output connectors.

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I'll have to do a bunch more disassembly to test those — would the battery charge successfully if those fuses were blown, though? What are they protecting? I measure 3.4V across the power pads on the logic board with either battery, power supply, or both connected. And there's 12.6V across the left IO board power connectors with the power supply connected (12.4V with only the battery). So power to the logic board seems to be working overall, but I'll dig in and find the fuses if you think they could still be the culprit for some reason.

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If yoy need some more help ie pics i.m able to peivide these if you give me yoyr e-mail address.

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Has anyone found the solution to this?

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I'm also looking for a solution to this. Having the same problem after trying to boot my MBP mid 2011 after vacation...

It manages to boot with fans full speed randomly sometimes, but otherwise it's the same thing; booting 1 sec and shutting off, booting 1 sec etc etc.

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This is a very old question do you have A1226 or A1260 model or something else?

I would recommend you create a fresh question with your details.

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Hi all,

I just got this problem as well.

I recorded a video and post it on YouTube

Any help with this issue guys ?

https://www.youtube.com/watch?v=3Iwbf6xy...

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did you fix it? what was the problem?

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Julian will be eternally grateful.
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