Both USB ports of a MacBook were dead after a shortage or overload on a Ramps Board that was connected to the Mac via an Arduino Board.
Normally Mac OS shows a message that tells you that the USB device got deactivated due to a power surge on that port. In this case the message wasn't displayed. It was later displayed after a reboot. Anyway both USB ports were instantly dead.
Here and there in the internet people advise to perform a SMC reset. That was done but didn't help. But you should try the SMC reset first.
Make yourself familiar with the pinout of your USB cable. Find the ground (GND) and measure with a multimeter if there is still an connection between both ground pins of the USB ports.
Check that there is really no power between ground and the +5V pin of the USB cable.
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