Released June 2012 / Core i7 processor with Turbo Boost / Up to 1 GB DDR5 Video RAM

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Only boots when power button is held down; strange behavior

Hi everyone,

Any suggestions you have would be greatly appreciated! Here's the situation:

I just got my hands on a 2012 Macbook Pro 15". I got it pretty cheap because the seller said the computer wouldn't get past the grey screen or Apple logo when booting. I figured it was likely an issue with the hard drive and bought it anyway. Sure enough, when I put my own hard drive in there, the computer doesn't get stuck on the boot screen.

HOWEVER, it will only turn on if I hold the power button down until I hear the click/whirr of the CD drive. If I just press the button, the SIL will turn on once and then nothing. I don't think there are any mechanical noises when this happens.

Once on, the computer appears to work fine. It's a little sluggish to boot and to respond to inputs, but that could be because of the 8 year-old HDD running High Sierra (just as a tester), or because the OS was installed on an entirely different machine (2010 13" MBP, 2.4 GHz C2D).

Thanks for your input!


I've reset the PRAM/NVRAM and tried resetting the SMC, but I couldn't tell if anything happened.

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I would try to do a fresh install of the OS, and see if that helps. This does seem like its an EFI firmware issue. perhaps updating that might help the situation?

Open up Activity Monitor and see how much of the cpu is being consumed. If you have the kernel_task process consuming >300% of processor, then it surely is a thermal sensor problem, like my MBP suffered just this week.

I would also suspect some power issue. If it turns on holding the button for 10 seconds, then you could perform a power cycle and see if that normalises things back.


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Down load this app: TG Pro so you can check the thermal sensors. I’m suspecting the system had a liquid spill and the palm rest sensor is messed up which is why your system is so sluggish and the power button is not working correctly. Let us know what you find.


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Re-installed the OS, as per Aman Patel, but that didn't really make a difference. After running for ~ an our, the palm rest temperature is ~ 30 ºC. I noticed that the system processes are using about 85% of the CPU (process is kernel_task).

Are the power on and kerne_task issues separate?

Yes, the two issues are separate but could be related to a possible liquid spill.

So the sensors are all working then? As well as the fans?

The sensors are all showing reasonable operating temps, though the CPU seems a little low ~ 55°C.

The fans stay at 2000 rpm. I can manually set them to run higher with TG Pro and they will respond.

I also ran EtreCheck, and it reported a battery failure. I noticed the laptop has trouble waking up from sleep sometimes, especially if the lid is closed. I've read that a very large kernel_task load (more than 100%; about 500-600% in my case) could be due to the system throttling because of a bad battery. When I get home, I'll try replacing the battery with a different one.

A weak battery can also be the cause! Time for a fresh battery!

Tried the new battery, but no success. I ran AHT and got the following error: 4SNS/1/40000000: IPBR-18.330.

Looking around, this sounds like damage to some power bus, possibly from a liquid spill. So does this mean I need a new logic board?




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