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Hi, I´m having some issues with my MBP mid 2012, it won’t turn on unless I hold the power button for about 10 seconds. I already tried safe mode, SMC, PRAM and nothing seems to be working. I even installed the latest OS available but nothing happened (it didn’t even changed anything in the system) I also tried factory reset and once completed absolutely nothing changed. All my programs are there and it looks like it was just off and then on. I took the cover off and unplugged the battery but nothing happened. I’m currently using Yosemite Please help!!! Thanks!
See if shorting out the power pads boots up your system. You should only need to short the pads for a moment (Red circle.
If it works reliably then the issue is within the upper case or the ribbon cable. Review Step11 in this IFIXIT guide: MacBook Pro 13" Unibody Mid 2012 Logic Board Replacement. Do be careful! the slide can easily be broken and you might find using a small piece of electricians tape folded over can help in pulling out the ribbon as well as pulling it back in. Update (04/26/2017) ’ OK, lets backup here a moment… You stated the system would turn on but does it stay on? If This is not the case then we are going down the wrong path here. If the system won’t stay running then we need to review the power systems. Using the battery test button are you seeing all of the LED’s lit? If not are you only seeing the first LED? When you plug in the MagSafe charger is the MagSafe connector LED a bright Amber or Green? Review this Apple T/N: Apple Portables: Troubleshooting MagSafe adapters Tell us if you find anything.
