Hi there i have the same mac and I have the same problem but power button don´t works the light on keys don´t work the fans are 100% cpu kernel task uses 200% cpu. I allready change the disk for 1 ssd install last version of OS sierra but no luck I try tu update smc it says that update but when i see version is the same. the power button works when i made key combination like option + comand + power so is not hardware fault . i have the web cam broken can be from there? is there any solution please help me this is my first mac and Im regreted all ready