Can you backup your harddrive, without turning on your PS4?

Whenever I try to turn on my PS4, I get a message that says something like this: "PS4 can't turn un, update to 4.71 via usb".

As I'm trying to get plat in AC:Brotherhood, I really don't wanna initialize without backing up my saved data, but I don't know how, as I can't turn my PS4 on.