After a long period of random crashes, my Mac will not turn on.
After a month of issues and troubleshooting regarding my Macbook Pro, I am now turning around the community to fix my problem.
The machine that is causing me trouble is a Macbook Pro 15inch mid-2012 running with Sierra. The only issue that I ever had with this machine was a faulty screen that was changed about two years ago by Apple.
About a month ago, I started experiencing crashes while using demanding Apps like video games, design Apps or watching a movie on my TV via HDMI.
My computer would just shutdown suddenly and after reboot. No error message/crash report would show up. It was like nothing happened and my Mac would just try to reopen all the applications that were opened before it crashed.
The particularity was the pattern of these shutdowns : I would have my Mac running nice for lets say 2 hours, then it would crash. After reboot it would work for 40 minutes then it would crash. After the second reboot it would work for 15 minutes then it would crash again and so on until I reached a point where my Mac would crash just after the boot chime. I would then leave my computer unplugged for the night and I would be able to use it again the following day, my mac following the same pattern again.
I first thought it was RAM/graphic card/logic board related because demanding Apps would cause my mac to shut down no matter what. I tried a few things :
-I first did a clean instal of Sierra to make sure it was not software related. It was really difficult as Mac crashed 3 times in the process. The clean instal seemed to stabilize the crashes for a while then it started again.
-I installed Mac Fans Controller to see if the issue had something to due with the CPU's temperature. My compter would still shut itself down with a cpu temperature of 80 degrees which I don't think is a lot.
-I went to the genius bar but they couldn't run any test because I didn't have any serial number on my logic board.
I was really surprised because I never had any logic board remplacement. They told me that the Apple Official Retailer might have changed my logic board when I had my display changed two years ago.
After some search I have found that my logic board was not changed and that other people had experienced a lose of serial number while updating the OS. So I don't know if this has something to do with my crash issue but I think it is something different. So I used Apple Blank Board Serializer to put my serial number again.
-I managed to pass three extended Apple Hardware Test which said everything was fine even though my Mac crashed during five other ones
-I tried to test my RAM by running memtest86+ which said everything was fine and by switching my RAM on all the different position that I could.
-I changed the Hard Drive and did an other clean instal which ran smoothly and seemed to fix the issue for a day and then my Mac crashed again.
After all of this I realized that the crashes looked more like a power loss. I used a have an IMac and the crashes I experienced with my MBP look like the crash you got from a sudden power loss on your desktop computer if you unplugged it while it is on.
So I started playing with the SMC and realized that a SMC reset would help my MBP to boot again after it had reached its un-bootable phase (crash after the chime).
Something curious as well that happened : My Mac crash and I want to do a SMC reset. I unplug the MagSafe, hold the keys for ten seconds, plug back the MagSafe but then, the Mac will power on by itself, without me having to touch the power button. I even noticed that if it crashes while using the battery, if a do a SMC reset then plug the MagSafe, it will turn on, crash during the chime, turn on again, crash during chime, etc... For 3/4 times before booting completely. (But without me touching the power button)
So I am no expert but all of those strange behaviours seem to indicate a power supply issue.
But then, yesterday, my MBP worked fine for 4 hours then I started a video game to test it. It crashed after 5 minutes but this time, it won't turn on again! Even if I do a SMC reset. If my Mac if unplugged and I try to boot it from the battery, nothing happens when I hit the power button. If I plug the MagSafe, the light turns green and I can hear/see (I removed the lower case to watch) the fans clicking/shivering and I can hear a hissing sound coming from the MagSafe adapter!
I have no clue what to do next and I am afraid I have caused extra damaged with all those turn on/turn off phases.
I would really appreciate feedbacks if you have any clue of what may be the issue.
Thank for reading me, sorry for the long post but I think it is better all the info available. I also apologize for any grammar/vocabulary mistakes as English is not my primary language.