Serial woes—Can read, but cannot write to serial
I'm using a 4G model, and I can load both the Ubuntu 18.04 and Debian 9 images just fine. HDMI displays just fine, and keyboard and mouse are working as expected. I just want to be able to interact with this device on the serial debug console.
I've tried the picocom and minicom examples, and they work insofar as I can read the console data. Why can't I write? Am I missing something?