'Anyone have luck flashing a Sonoff IW101 device with Tazmotizer?

[KarlHanzel]

I have one of these: https://sonoff.tech/product/wifi-smart-wall-swithes/iw100-101

I've got it set to go with a recent copy of "tasmota.bin", that i recently downloaded from here: https://ota.tasmota.com/tasmota/release/

I'm on a Mac/macOS (Catalina/10.15), and am selecting my "cu.usbserial-A904QHYG" port. I get the same results if i try selecting the "tty.usbserial-A904QHYG" port.

At the Terminal window where i have launched tazmotizer.py, it emits:
esptool.py v2.8
Serial port /dev/cu.usbserial-A904QHYG
Connecting......................................_____

But in the pop-up window it never "connects", even though i see my Adafruit FTDI device flashing red & green LEDs (encouraging, at least). Then after trying for a bit, the pop-up is replaced with another: "Failed to connect to ESP8266: Invalid head of packet (0x00)".

'Tried with switch itself turned both off & on, and after long-pressing touch-button to "reset" the device.
Same result whether i tell it to “Erase before flashing” or not.
No joy, whatever i can think to try.

I've never done this (Tasmotizer flashing) before, so am ~stumped.
Thanks for any insights!!

Karl
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