As of 2018-12, I believe that I might have fried the UART on this board when I burnt my last UART to USB converter by connecting ground to 5V.
Linux kernel logs don't show, but do show with the exact same components on the Pi 3 (SD card with
enable_uart=1+ image Raspbian Lite 2018-11-03 and UART cables).
cat /proc/cpuinfo: 00000000a50c1f69
Datasheets: Raspberry Pi 2.