update to my problem.
Thanks to @ [paulscode] (Profile - paulscode - Start9 Community) (you rock !!!) I adapted his solution to the Dell Optiplex 7040 , and StartOS is finally installed and booting easily.
Gratitude (
here is the version of the procedure adapted to DELL machines for people who will encounter the same issue :
Based on the provided information about your OptiPlex partitions, here is an adapted version of the tutorial with the bash commands separated.
Adapted Tutorial for Your OptiPlex
Please note: This tutorial assumes your OptiPlex has a similar boot issue where it doesn’t recognize the bootloader after installation. The key difference in your setup is the split EFI System Partition (/dev/sda1) and a separate boot partition (/dev/sda2). This tutorial will focus on the EFI partition, as that’s where the bootloader files need to be.
You’ll need a keyboard, mouse, and monitor temporarily, along with a bootable Linux USB thumb drive (like Ubuntu).
Step 1:
Complete the initial StartOS installation process. When the OptiPlex reboots, it won’t launch StartOS. We’ll fix this in the following steps.
Step 2:
Attach the keyboard, mouse, and monitor, insert the Linux USB drive, and power on the OptiPlex. Boot from the USB drive.
Step 3:
Open a terminal and enter the following commands one by one. Adjust the device paths if your partitions are different than /dev/sda1 and /dev/sda2.
# Mount the EFI System Partition (/dev/sda1)
sudo mount /dev/sda1 /mnt
# Make a folder under EFI called "BOOT"
sudo mkdir /mnt/EFI/BOOT
# Copy shimx64.efi as BOOTX64.EFI
sudo cp /mnt/EFI/startos/shimx64.efi /mnt/EFI/BOOT/BOOTX64.EFI
# Copy mmx64.efi
sudo cp /mnt/EFI/startos/mmx64.efi /mnt/EFI/BOOT/
# Copy grubx64.efi
sudo cp /mnt/EFI/startos/grubx64.efi /mnt/EFI/BOOT/
# Create grub.cfg
sudo nano /mnt/EFI/BOOT/grub.cfg
Enter just the following two lines into the nano editor:
search --no-floppy --file /EFI/startos/grub.cfg --set=esp
configfile ($esp)/EFI/startos/grub.cfg
Then save the file by pressing Ctrl+X, then Y, and then Enter.
# Make sure writes are finished
sync
# Unmount the EFI partition
sudo umount /mnt
Step 4:
Reboot the computer. StartOS should now launch.