Hard Disk Problems with Windows Installation?

I actually have Linux on my laptop and wanted to switch to Windows now. Have a bootable USB stick created and have the BIOS changed so it boots from the USB stick. I came also into the Windows Setup. After I've chosen custom installation, I have to choose where I want to install Windows, but I can't select any of the three partitions. It just shows me an error message that the partition is an EFI system partition, but it needs to be installed on an NTFS partition. When I try to format them, I get only an error message because they contain important files or applications of the computer manufacturer and therefore could not be formatted.

After that I stopped and now I can't even enter the BIOS. The screen flickers all the time and all that is displayed is the boat menu. The first is ubuntu, then ATAPI CD, ATA NVMe, PCI LAN (IPv4) and last PCI LAN (IPv6). I can't move or select anything. And with Esc, it just starts again. Can someone help me?

I suggest you use a bootable stick with Linux Liveboot and format or delete the partition with the help of the tool "GParted". Afterwards you can format the partition and install it on the Windows installation.

Linux has a filesystem Windows does not care about, Windows can't read, let alone format, Linux file systems.

What you can do with the Windows Setup DVD / USB stick, delete the partitions. You have three partitions, you have to look at which of the partitions are the drivers. Leave this Efi system partition alone if Windows was already installed before the Linux installation.

These three partitions are the root, the home, and the swap partitions that Linux created during the installation.

The main partition would have to be deleted with the Windows USB stick. Then the Windows installation routine will be able to reformat this indefinite hard disk space.

Hard Disk Problems with Windows Installation?

Before even more half-truths and coffee grounds come here as answers:

Please start a Linux live system and show what is being output when you run it in the terminal:

fdisk -l # That's a little L

but I can't select any of the three partitions.

That's right, because Windows wants to have either a partition with NTFS (also FAT) or an unformatted partition to install. Alternatively, you can delete a "badly formatted" partition in advanced mode and then create it again.

When I try to format them, I only get an error message

If the installed Linux is no longer needed, then you can simply format everything or delete the partitions.

After that I stopped and now I can't even enter the BIOS.

That certainly has nothing to do with the installation attempt.

Linux Hase