Howdy Terry,
I am very sorry you are getting a white screen. I would love to help you figure this out.
It is very probable that you updated only one of the plugins to 4.0, and some of the others are still on a past version. Unfortunately this can cause white screens, which is our bad. We did not test out updating one at a time before launching 4.0. 🙁 But there is a solution! Using a file manager, such as the Blue host one or an FTP program, rename the plugin folder from the-events-calendar to the-events-calendar-temp. Now try visiting the WP Admin. It should load as renaming the folder deactivates that plugin. If that does not load yet then try renaming one more plugin folder, the-events-calendar-community-events to the-events-calendar-community-events-temp. Now load WP Admin. From there update all of the The Events Calendar addons to 4.0. Then when they are all up to date, rename the folders back to their original, and reactivate those two plugins. Presto!
Does that all make sense? Did that work for you? Are you still seeing issues with your theme? Please let me know.
Cheers!
– Brook