The board used on this thing is an ESP32. Some ESP32s have a physical button that must be pushed in order to put it into “flash mode”… basically unlocking the ability to write to the device.
I had this happen months back, and what I ended up having to do was locate the button’s approximate location inside the case, drilling a small hole above it, then using a paper clip to press the button. Once I did that, I had no problem uploading the firmware. Suppose I could have just pried open the case, but it was glued together and I didn’t want to chance it.
Second on the drill-a-hole thing, pressing the button to flash it was a roadblock for me as well. I tried getting it apart by dremeling the glue on the corners, but ended up having to break it open anyway. Support will also send you the files to make a new case, if you’ve got access to a printer.
Here’s how to put the Nimble Connectivity Module in download mode:
Gently pull the knob off. Gently open the case to the connectivity module and pull out the board. On the bottom of the USB-C port there will be 2 tiny buttons. One is called boot, the other is called EN. When you’re uploading to the board, you should see the “Connecting…” message in the terminal. Hold both Boot & EN while this is happening, then let go of EN. It should now connect. Let go of Boot. Hopefully this helps.