Alpha Client Bug

So i was playing League of Legends on the Alpha client and I had just finished a game as Riven (Don't hate me) and we were about to win and the enemys forfeit which caused two nexus explosion noises. I do not know if that was the problem but when i exited I got a notification saying I had earned a key. The problem was that the screen is permanently black after that. I can look at friends and such but I am not sure if it is a Alpha Client bug or my computer. If you guys could help me that'd be great thanks!