After overwriting an SD card with the ancient OS image, and resetting it to 'factory settings', I had issues connection to WiFi, or getting the macOS Kobo app to update the 'firm'ware.
This worked:
Again wrote the image to SD.
Downloaded Aura HD firmware update here:
https://pgaskin.net/KoboStuff/kobofirmware.html
Extracted the files to /Volumes/KOBOeReader/.kobo, according to this thread:
https://www.mobileread.com/forums/sh...d.php?t=145177
The next boot sequence will looked messed up. A kind of ghostly sideways and repeated "don't turn off" (🚫+⏼) with the same repetition of three dots circling.
Your Kobo still updates to the latest OS, even though the update developer couldn't get the screen to work properly 😅.
Now you can reset your Kobo Aura HD, it will connect to WiFi, and will you can do the rest as expected.