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I replaced the MagSafe board on my MacBook Pro 2012 unibody and had to do the process of starting it by holding power button for 10 seconds and then plugging in charger while battery was unplugged. This worked, but the fan ran at full speed with no load and the battery could not be detected. So I decided to do an SMC reset as per Apple’s support recommends (shutting down, holding power, left shift, control, and option for 10 sec, and then turning back on). The problem is that the computer will not turn back on now. I have retried all the methods I have read. Any advice would be appreciated! Thanks
Given the age of your system I would recommend you replace the battery if you haven’t already. What is the color of your MagSafe charger? Amber or Green, if its Amber let it charger for a good 8 hours did it turn Green? If its green already then you might have a logic board problem with in the charging logic. This can happen when using 3rd party chargers OEM MagSafe Chargers vs Cheap Imposters: Teardown for Truth They also tend to carbonize the MagSafe contacts so do make sure the connector contacts are in good shape Apple Portables: Troubleshooting MagSafe adapters
