If you have unstable connection, the navigator may think that the download has finished . Check if the downloaded file is 552Mo. If not, that mean the download has crashed. In this case, use a free dowload manager . I had this issue because I'm using a shitty hotel wi-fi, and after 10 try it was still impossible to dl the file properly. With the download manager, it allows the dl to restart from where it crashed. If your dl file is already 552 Mo, then I got no ideas !