~/brewblox directory is not special. It is a directory like any other found on Windows, Mac, or Linux. It is relevant to Brewblox because it contains the configuration and data files required to start and run the system.
During installation, a new
~/brewblox/ directory is created during the
brewblox-ctl install command.
I’m honestly still not entirely sure how or what you updated, as Debian updates are much more involved than simply hitting shift during startup. (I think you updated the
raspi-config configuration tool itself)
You can do a directory search to check whether brewblox was installed somewhere else:
find / -maxdepth 5 -type d -name brewblox 2>/dev/null
If this does not yield anything, I recommend a fresh install (follow the install guide from the start, including the SD card flash)