This is on a MacBook Pro. Hearthstone is upgraded to 29.6 and I was once able to launch Hearthstone, purchase mega bundle and now started seeing Black screen after launch. I have tried repair multiple times, also did a uninstall & install.
Update: It works if I run it in Windowed mode, does not work if I run it in Full screen. I then see Black screen
Same problem on my Mac. How do I force it to run in windowed mode? It always automatically launches into full screen when I open it. I looked in the game settings, but I don’t see any settings for that. Is there a command line I should add to my settings?
Also having this same issue. Not sure how to get it out of windowed mode either.
Actually I take back my other comment, I was able to get into windows mode by pressing the F3 key and clicking the minimize button on hearthstone. It worked
Oh good, I’m glad you got it to work. My minimize button doesn’t show up when I press F3 
I guess I need to try something else.
Problem exists in Windows as well. I only play in windowed mode so it opened in windowed mode. That fix doesn’t apply here, unfortunately.
I pressed ‘fn + F3’ and nothing happened. It’a a black screen. Contacted Blizz and they came back with a generic answer
How did you get it in window mode from the black screen?
If I press esc, I can hear the sound effect for the menu coming up, but I’m left clicking around a black screen with apparently no interaction with any buttons.
To the right of the play button is a cog wheel. Scan and repair works.