Hi, I’m sorry to hear that.
So to clarify you are unable to configure widgets via the Appearance → Widgets admin screen? If so (though I appreciate you already have clearly spent time troubleshooting) can you confirm that this is still a problem even if only The Events Calendar and Events Calendar PRO are active along with a default, unmodified theme?
Can you also confirm which plugins you updated? Are you referring to the recent updates for our own plugins?
Thanks!