El Capitan - Arduino IDE serial port problems

No joy here. I have an out of the box official Arduino Uno R3, the latest version of the Arduino app (1.6.8 Hourly Build 2016/02/02 running on a Mac with the latest version of El Capitan), and I've selected the proper board (Arduino Uno) and serial port (in my case /dev/cu.usbmodem141111 (Arduino Uno/Genunio Uno
). I'd tried disabling SIP, but still nothing.

When uploading, I get the dreaded

avrdude: stk500_recv(): programmer is not responding

I've been searching forums for almost two hours, and no one seems to have a solution.

Has anyone yet been successful?