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Original post by: karunadheera ,


Same thing happened to my early 2011 MBP. The proto board I was testing (AMS1117 3.3V regulator on PIC microcontroller with USB function) suddenly failed and fed 12V on usb rail. Mac suddenly shut down on me. I unplugged the usb at once. However that USB port never worked after that. Even the remaining one does not provide enough power to connect up an external HDD or Pickit Programmer now. Only solution was to use a powered USB hub.

This is the part I suspect which had failed due to high voltage.