If you see the error message bootrec /fixboot access is denied, boot to Windows Recovery using the installation media. Open Command Prompt and DiskPart to locate the EFI partition, assign it a temporary drive letter, and restore the boot files using the command bcdboot. Then repeat the bootrec command. This procedure usually restores the boot configuration and solves startup issues caused by a corrupted system partition. Read more: https://datarecovee.com/bootrec-fixboot-access-is-denied/