I have upgrade failures occuring over multiple RealPresence Group 700 endpoints trying to update from 6.1.7.2-510016 to 6.2.1.1-570046.
The issue is eerily similar to that encountered in this Polycom Knowledge Base article. That being the case, I have tried the USB Factory Restore on one of the endpoints as a trial and it does seem to resolve the issue, however it is a major pain as uploading a System Profile alone does not restore Contacts, Speed Dials, Thumbnails, or Background images, and the annoying Maximum Ventilation Option is restored. One of these endpoints is remote, requiring an interstate flight if this is the only means of dealing with the issue.
I am sharing my experience today for the benefit of others and to canvas any formal explanation and suggestion of alternate workaround. Thanks.