I tried the trick you told me with the elilo.conf file and the bootx64.efi in the /efi/boot directory!.
I succeed finally to boot on the usb key in UEFI only mode:
It was written :
Then it loads 2 files, and writes "done" for each of them. Then it stops loading and the usb key turn off. The screen stays the same....
What 's the matter ?
Thank you !