STORE NOT OPENING: showing error code and Amumu (?)

The weekly sales was supposed to reset tonight and I was hoping to buy a Battle Academia skin on sale. But Alas! The store is not opening at all for the past 3-4 hours. Whenever I click on Store, it loads for a minute and then shows a error code with Amumu's drawing in the background.

I tried re-logging multiple times and still facing the problem. There isn't even any notification about the issue.

Please Riot check the issue ASAP.