Hi. My retina 15" has stopped working. It loads a blank screen. In recovery mode it can't find the internal storage. Before this it kept having weird freezes where you'd have to turn the machine off, especially if you moved it. Those have been going on for months since a apple repair on something else. It's out of warranty and also there's no Genius Bar appointments available for about 10 days in the nearest dozen apple stores, I need the machine for work so I can't wait that long. Any ideas of what to do?