I have the Anniversary Update on a USB drive. I could do a clean install from there, right? I assume you mean do a clean install. That's more work than I expected to do. I have another Surface Pro 3 that updated without incident. One difference is that the failing one had the update blocked until a few days ago. I would start the WU of 1607 and leave it and when I came back I still had the old version, no message. Finally I watched it and saw it fail. At least using MCT gets me an error message although it doesn't help.