Leave the 5V wire coming FROM the PC open, and connect the 5V wire going TO the Mega to my 5V power supply
The solution I used was to carefully cut a section of the jacket from the USB cable, then: I would like to power my Mega with my own 5V switched power supply - and - update my sketch from the PC without unplugging/plugging the USB cable. Like others who have posted to this thread, my Mega is buried in a project box and hard to access.
