I cant go to league? Riot please help

Alright so i decided to go on league and i saw an update talking about the new client. I was like wow! Already?! So I waited for the update to finish up by you know eating and doing some work. I heard a noise of the game being done downloading so i was like " Alright! lets see whats ahead of us" So then i clicked the play button, but it didn't pop up. At first i thought it was my computer being slow but i waited for hours. Then I knew something was wrong. So i did my usual things and just exit out and go back in but afterward it would say " Another instance of a league client is already open. Please close it and try it again" So then i saw a navy black square in my screen. That was just that and i couldn't even exit out of that square box thing that the game claims to be another league client. So then i restarted my computer hoping it would work, but it didn't work. It did the same thing as before. I thought " I'm just going to uninstall then reinstall" I did and it did the same thing as before. I don't know what to do with this new league client not letting me get on league, but i'd be happy if someone can help ;D