Arria 10 aocl diagnose failed

The driver is certainly working correctly then. I can think of more reason that it might not be working for you which I myself also encountered before. Since Terasic distributes their Linux BSP as a zip file which doesn't preserve file permissions, the diagnose script from the BSP might have incorrect permission and that is why it is giving this error. Try chmoding all the files inside the BSP_install_folder/linux64/libexec path to 755 and retrying the command. Better yet switch to root user temporarily, make sure the driver is loaded correctly also under the root user, and then running the diagnose command under that user.