Well, shoot. A few minutes ago, our team discovered that a problem with Amazon Web Services (AWS S3) is preventing our users from being about to log in to Revision Assistant. We use AWS S3 as a bulk repository for a variety of the documents and files that keep Revision Assistant running smoothly. We did figure out, however, that users who were already logged in when AWS S3 threw its tantrum would still be able to perform most tasks in Revision Assistant except for viewing our Rubrics and Assignment PDFs. Unfortunately, we do not have a quick fix for this sudden Amazon hissy fit and many other websites that use this service are also experiencing the same problems. When we figure out a solution you will be the first to know. (You can also follow their progress at https://status.aws.amazon.com/
Until then, Amazon Web Services is in time-out.