I really like this thing, it's a Raspberry Pi 3B+, with a Google AIY Voice HAT, and a nifty acrylic case instead of the original cardboard one.
I've had it for a while though, and it was still running Raspbian Jessie. Nothing wrong with that, but there are new versions of the AIY Voice software, that can do more things than the original software. I'd rather like my other Raspberry Pi systems to be able to use it as a voice input and output, for example. To do that requires Raspbian Buster...
So that I wouldn't lose all the setup information on the Micro SD card, I decided to upgrade in place. Bad idea!
The upgrade, two steps, via Raspbian Stretch, takes hours. Stretch booted OK, though, so I continued. Buster wouldn't boot up...
All that took over half a day, and it didn't work.
After a bit of head scratching, and a certain amount of exercising my extensive vocabulary of rude words, I did what anyone sensible would have done in the first place, and downloaded a ready-made image, from GitHub and flashed the micro SD card with Balena Etcher.
I had saved copies of the setup information files handy, which I copied in with WinSCP (freeware that's so great I paid for it!), rebooted the Pi, and suddenly it worked!