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It would have been good to know why "Replace Partition" failed though... maybe you could try again with starting calamares from the command line:
sudo calamares -d
and paste the output here if it fails again with "Replace partition".

Since I wasn't able to boot... which command line?

Ah... and I forgot to mention... I did something different this time: I also created a swap partition. That did not happen, when I used the "Replace Partition" option. But that shouldn't affect the installation of the bootloader.

Commandline means the terminal / Konsole app

Yes, use Konsole from the live media when your try another install.
Boot the live media and open konsole, then type: