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I upgraded my macbook pro mid 2012 ram from 8gb to 16gb today. During that process I wore a static wrist guard and unplugged the battery from the connector. After installing the new RAM and replacing the battery connector, the laptop would not turn on (no on screen and no sounds) and the charger will not charge the battery. I tried reinstalling the old RAM and and smc reset but no fix. If anyone has any issues similar to this and have a solutions please let me know.
In principle nothing should go wrong with a simple RAM replacement, especially when one puts utmost care by wearing a wrist wrap. Since you disconnected battery, double check the small battery indicator cable sitting beside battery is correctly in place. Try starting your Mac without the small connector and battery disconnected too. Double check all cables connecting to the logic board are firmly in place. That’s about all you can do..if nothing works it might be either an unlucky coincidence or an incident, but would need some board testing to get further.
Disconnect the battery from the logic board and the mag-safe adapter. Press and hold the power on button for 10 seconds. Reconnect the battery then the mag-safe and you should get a spontaneous reboot if the logic board is good.
