We had a similar issue. Although I can not remember that we updated the theme. The website was blank for 1 or 2 days. But management to get into the admin section. WordPress told that the theme was broken, and after deactivating the theme, WordPress said that a file of the theme was missing. I think it was the Style Sheet. Removed the theme’s directory and reinstalled it. Didn’t work first time. But later tonight it did work. Think we get it working again. But it’s not a good experience.
