Chosen Solution
So my 2012 15" Macbook was working fine. It will no longer power on if I press the power button. If i hold the power button for 10 sec. then plug in the mag safe adapter and hold the power button for another 5 seconds it will turn on but the magsafe light LED turns off but is still charging. I can then shut it off and turn it on repeatedly no problems. As soon I unplug the mag safe and plug it back in the led on it comes back and the Macbook will no longer power on unless I repeat the steps outlined in bold above. I have erased and reinstalled MAC OS Catalina.I have erased and rolled back to OS Mountain Lion which came installed on the computer.I have unplugged and reconnected all adapters and plugs internally.I have tried different RAM and SSD’s.I ran disk utility and it says the drive is OK.I tried to hold “D” and run the diagnostic but it goes to itnernet recovery then black screen that says Error: 8000000000000003, Cannot load ‘EFI/Drivers/TestSupport.efi’ Status: 0x00000003 My head hurts to why this is happening and i have ran out of options. Does anyone have any idea on A: What generally causes these issues? B: What is the mode called when it go into when i hold power button for 10 sec then plug in magsafe and hold for another 5 seconds? and C:Is this software or hardware? and what can i do to fix this. I find it odd that it will power on if i do that specific sequence so it tells me it might be software? or maybe the hardware is not correct and this mode scales the RAM or SSD so that it can function correctly with the machine? Thank you for any help!!
The charging logic on your main logic board has problems! There are a set of MOSFET’s which switch the power between the DC-In board to either the battery to charge it or th the logic board to run the system. There is also a set of MOSFET’s which switch the power from the battery to the logic board. One of the causes of these failing is using a cloned charger OEM MagSafe Chargers vs Cheap Imposters: Teardown for Truth At this point you’ll need to make sure the MagSafe connector on the system is clean and not carbonized. Review this Apple T/N Apple Portables: Troubleshooting MagSafe adapters. If it is then that’s a sign of arcing from a cloned charger Lacking safety features, cheap MacBook chargers create big sparks. You’ll need to find someone with deeper skills to trouble shoot the logic board. Let’s see if we can narrow down which side of circuit is bad. You’ll need to open up the system and inspect the logic board for signs of a burnt chip.
