I added the apache2 access and error logs. It does not appear that the issue was caused by intrusion or denial of service, but there may be a few things in the logs worth taking a look at.

Removed message regarding outage by uncommenting the button and commenting the error message. Added additional comments to the page to show which bits need to be commented and uncommented during an outage. Checked it on bioviztest host first to check that the system is working properly before removing the message on the main production host. I was able to log in and view my files listed properly. Updated production site and changed its "stack" tag back to "Prod".

Moving to Closed.

From Sriram Srinivasan on the CyVerse team:

Hi Nowlan
We did have outage this morning. It should be fixed now.

Thanks
Sriram

Note: connect.bioviz.org is returning 503 response. Terrain APIs are returning 503 response including access token. Tried local system and bvctest6 as well – 503 response everywhere. When the old access token is used in Postman for all the other Terrain APIs, instead of getting Unauthorized 401, the response is 500 server error. It seems like an issue from Cyverse but the Cyverse status page is all operational and Cyverse DE is operational as well

[~aloraine] modified the BioViz Connect start page to disallow login while we try to fix the problem.
When the problem is fixed, don't revert the changes. Instead, uncomment the login button and comment the "sorry it's broken" statement that was shown instead of the login button.