I helping out a friend here.... I got that 2013 MacBook (A1425 with 500Gb HDD) that was recently upgraded to 10.11.4 - after that things went sour. Right after installing it worked only when NOT charging. When connecting power it freezes and crashes shortly after. No suddenly it doesn't work at all. When I switch it on now, it loads for a while, I see the Apple logo, the loading bar (up to 80%), login screen, up to the mountain wallpaper... and then freezes after about 10-15 Seconds. Need to press power for 10 Seconds to get out. Any idea how to troubleshoot this issue? ------ Same added info: It boots fine in Safe Mode. Diagnostics: No issues found Seems the fan doesn't spin Is there any specific diagnostic in the console that could give a hint?