Finally, I managed to find workaround. I had made a copy of /EFI/BOOT/grubx64.efi with the name mmx64.efi on the bootable medium. After this, the USB disc was able to boot again and I was able to continue with installation process. After successful instalation wverything was OK.
Finally, I managed to find workaround. I had made a copy of /EFI/BOOT/ grubx64. efi with the name mmx64.efi on the bootable medium. After this, the USB disc was able to boot again and I was able to continue with installation process. After successful instalation wverything was OK.