have the same issue though the power button answers when reseting SMC - shift +ctrl+alt+cmd+power button but not otherwise only on this stroke..very strange..
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UPDATE!
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Allright, just after i was writing the previous answer/question i was playing with the machine and measured the voltage on the connection to the logicboard on the logicboard side and not on the Trackpad side, i kept pressing the power button and wanted to check if there is any reaction, at the beginning there was nothing and than i got 5v on pin number 4 or 5 from the left this pins normally gives 3v when turned off and 5v when turned on..now the power button works again..il let you know if it keeps that way.
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but i obviously shortened something in there that activated the pin again.
have the same issue though the power button answers when reseting SMC - shift +ctrl+alt+cmd+power button but not otherwise only on this stroke..very strange..