[timothy.reed]

Upping the baud rate to 115200 allowed me to see log data off the port - thank you!  When connecting, my Tangera goes dark/unresponsive and I get this response on the port:
ets Jul 29 2019 12:21:46
rst:0x1 (POWERON_RESET),boot:0x7 (DOWNLOAD_BOOT(UART0/UART1/SDIO_REI_REO_V2))
[color=#666666][font=sans-serif]waiting for download

Ah, this sounds like your device was being put into firmware update mode. The RTS/DTS signals are used for this, which *normally* isn't an issue because most serial interfaces don't really touch them. Can I ask when program you were using to view the serial logs? Maybe we should warn folks about this.

I used the Mac third party app Serial 2, which seems to be the most popular Mac app for interacting with serial ports, to connect. I've attached a screenshot of my settings. Fair warning that I haven't had to connect to a serial device in decades so may have data bits, RTS/CTS, etc. all wrong.

Now that I know the correct port speed, I was able to use screen to connect. Here's the command line I used:
% screen /dev/cu.usbmodem2101  115200
This gives me a "→" prompt; "help" shows me the various commands "lua", "luarun", etc. To test I ran "haptic_effect" figuring it would be harmless 'til I realized I didn't know how to terminate a Tangera console command. Control-a k dumped me out of screen and unplugging my Tangera and turning it off stopped the haptic element from doing its thing, but there's probably a better way to do this.

Hope this is useful. Please let me know if there's anything else I can do to help.