macbook pro 15” Unibody A1286 mid-2012
i7 2.3GHz 16GB
i had similar situation, my symptoms including:
kernel panic errors
crashes from any movement
3 bongs of death
slow boot ups
SMC Resets did not work
did not PRAM reset
based on feedback from here and Apple, i decided to swap out the logic board. followed guide, took 2 1/2 hours, but if i ever have to do it again, i’m sure the work will be much faster.
(+) ALL symptoms disappeared, although boot up seemed slow the first few times. seems to be coming back to (5400rpm) speed. it’s been thirty-six hours, so far so good .
(-) cannot access previous Time Capsule sparsebundle file. followed some convoluted (for me) Terminal commandsnon another website, but the protocol failed, so i’m starting my time machine from scratch.
the logic board replacement is something you want to be absolutely sure is necessary. there are a LOT of opportunities to break things you REALLY don’t want to break, but for the most part, the iFixit guide is great. be sure to read comments in any step you’re not sure about a LOT of hive knowledge there. allow ample time, make sure you have all tools, including the thermal paste and cleaner kit, be patient and organized.
replaced logic board