This is a follow up issue from https://tracker.moodle.org/browse/MDL-72188 where we implemented a support of new JS API for SEB client.  

As part of working on this tracker we realised that UI can be improved. 

Currently (assuming MDL-72188 is integrated) user lands on a quiz page and see  "The config key or browser exam key could not be validated ..." + bunch of buttons.

Then in case if key could be validated using JS API there is a message saying that "Checking access to Safe Exam Browser..." and if the validation failed then a modal pop up displayed saying "The config key or browser exam keys could not be validated". So pretty much replicating the same message that a user has already seen. Which is not ideal.

This issue is for changing this way of informing users and implementing the best UI experience.