@jimp Ended doing that, by re-installing from the original USB Stick that came with the minnowboard based boxes.
Then creating an easyrule that granted full access from the WAN, and from there I could take over.
Upgraded in two stages to 2.6.0 (first latest 2.4.x version), then switching to the 2.5 branch (which includes seemingly 2.6.0) and updating to that.
However, upon restoring the config.xml, the system got stuck installing packages.
So in the end, I had to delete the package lock, and reinstall all packages manually anyway.
There’s a constant issue with a couple of packages, in that they e.g. wont properly update, they have to be deleted and installed, each time there’s a new version. (squid I think is one of them)
At least things are up again, now. Thanks!