The latest patch seems to have introduced a startup error, so if you start the launcher and get a pop-up saying that it can't download the patch information or something, it replaces the Play button with Repair. Repairing does nothing. If, on the other hand, you just close the launcher and re-open it, there's a good chance that it'll open the launcher before giving the error message, in which case the play button will be accessible. At least, that's been my experience. Just keep re-opening the client a few times and you should be able to play
