@BTO
If you know you are going to wipe the entire disk, you might have more luck if you completely zero out the first few megabytes of the disk? This will effectively wipe the partition table and any bootloader code that was previously installed.
This is how you would do that:
1) Figure out what the name of your harddisk is (mostly likely /dev/sda):
sudo lslblk -f
2) Use the tool dd in a virtual terminal to wipe the first 16 MiB of your disk (assuming that your disk is named /dev/sda):
sudo dd if=/dev/zero of=/dev/sda bs=4M count=4 oflag=sync status=progress
3) Verify that the /dev/sda partition table has been wiped:
sudo lsblk -f
4) Do a normal install where you ask the Solus Calamares installer to erase the entire disk.
From what I recall, we have configured the installer to always use GPT partitions. If you are on system with BIOS firmware (not UEFI), a small 8MB compatibility partition will therefore be created right at the beginning of the disk, which will have GRUB2 bootloader trampoline code installed for being able to boot from GPT partitions.
5) Assuming that the Calamares installer now completes successfully, check the new partition table:
sudo lsblk -f
Hope this helps.
