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My gf has a severe issue with her MBP Mid-2012 (serial number is C1MK9X6ZDTY3; it is a MacBook Pro 13-Inch "Core i5" 2.5 Mid-2012). A few months ago I replaced the internal HD with an SSD. Everything worked fine. A new SATA cabled was also put in place.

Recently however the laptop had some issues. First, when pressing a certain area on the case, it would reboot. However, after rebooting I could work with it again as if nothing has happend. A few days later, it would again shut down, but then make 3 beeps while attempting to reboot. As several sources online state, this means faulty RAM. Intuitively I just tried to reboot again and the MBP worked just fine. My gf told me that there were cases where the diplays showed some glitches. Right now the situation got worse and the laptop cannot be used anymore. It boots, but then the "spinning coloured ball" occurrs. The laptop responds extremely slow. Finder cannot be opened, etc.

One more thing: She just told me that a few weeks ago she switched on the laptop with the power cable connected because the battery was empty. She then noticed some sort of "short circuit" when connected the cable. There was a tiny flash and it was as if something "burned". The funny thing is just that I would expect that the laptop immediately stops working. However it worked fine afterwards, but (obviously) slowly deteriorated as described above.

Other things I have tried:

  • I run Apple diagnostics. It said there could be an issue with the battery. I then did it again with power cable attached and it said there are no problems.
  • I removed both memory sticks (one by one) to ensure that none of them are faulty. With only one of them in use, the system behaved in the same erroneous way.

So what whould I do now? Can I do anything at all or should I go to a technician? Which faulty hardware could be responsible for the described behavior?

UPDATE: A short update: I bought a Samsung 850 EVO 500GB (see here: https://www.amazon.de/Samsung-MZ-75E250B-EU-interne-schwarz/dp/B00P73B1E4?th=1). Actually, I just remembered that I did not buy the SSD. The SSD is already a bit older, but I bought a new SATA cable, because the SSD wouldn't work internally. So I bought this cable: https://www.amazon.de/ireplacement-A1278-Drive-Macbook-821-1480/dp/B075PZ3PK5?th=1 With this cable I could use the SSD internally and everything worked fine.

UPDATE: I identified the root cause. See this thread now please: Extreme slowing down of MacBook Pro due to pkd process

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  • > First, when pressing a certain area on the case, it would reboot This alone suggests that there might be a tiny fissure in your motherboard, which breaks a circuit when you push on it. If you are sure that you want to repair it, I would start by finding somebody with the same Macbook and swap the RAM to see if that's the issue. I don't think that this is the most likely issue but you need to exclude the possibility of a faulty RAM before replacing the motherboard.
    – Tea Tree
    Apr 4 '20 at 19:22
  • Thanks for your comment. I explained that I reduced the possibility of a faulty RAM, didn't I? First, I removed one RAM stick and booted which resulted in the same erroneous behavior. Then, I removed the other RAM stick (and put back the first one), which resulted in the same behavior. So it should be certain that the RAM is not faulty. It could be that both RAM sticks are faulty, but I think the probability is extremely low.
    – beta
    Apr 4 '20 at 19:50
  • This sounds like a faulty reassembly - specifically long screws into short holes. I've seen this before. If you're not careful, you can "push" the logic board against the case causing shorts. Disassemble again, and put in only the minimal number of screws to hold things in - two or three should be enough. Run without putting the back cover back on. See if the problem goes away. I would also look for "extra parts" (you know, the extra parts you always end up when fixing something). You could have something loose in there mucking things up.
    – Allan
    Apr 5 '20 at 3:10
  • Thanks for the detailed and helpful instructions. Currently I was doing the analysis with the back cover off. So does that rule out your hypothesis of wrong assembly being the cause, right?
    – beta
    Apr 5 '20 at 9:53
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One thing that does happen at times with MacBooks of this kind (own one myself and had it happen to me) is that batteries can over time "inflate" and slowly but surely push themselves against something — in this case it would be weird if the something was the mainboard since it's not located under the battery but rather beneath it). But maybe you could take it apart and see if the battery looks odd or even a little blown-up and ask your friend if she ever replaced it before..?

Some basic steps to perform:

  • To rule out possible battery faults, you could take the battery out, then try turning it on with the power cable attached
  • Give the obvious "mac-things" a try such as SMC reset, PRAM/NVRAM reset etc.
  • Take out the SSD and attach it to another computer to see if you can start it up from there
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  • Thanks. I just connected the SSD to another MBP and the system then behaves exactly the same: it is really slow, the colored spinning ball appears all the time, and you can barely open any programs. So I think the SSD has an issue. Can you recommend any tools to check the health of the SSD? this is the next step I want to do.
    – beta
    Apr 7 '20 at 19:27

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