Hi, Nathan -
It’s hard to know what’s wrong without seeing some sort of output. Can you use gtkterm to provide a serial log of your beaglebone booting up?
Yogi
On OS X the device is often /dev/tty.usbserial or something similar, on Ubuntu you may not have permission to read/write to the device. Try becomming root first.
Also make sure the device file exists in the first place. On OS X you usually have to install software first.
ls /dev
and look for the correct device file first