Contrary to the circulating rumors, Prometheus is still a working firmware downgrade/upgrade tool and the word came directly from its maker tihmstar. That would mean jailbreaking with the Yalu iOS 10 JB tool from Luca Todesco remains a go and is even better with the release of Saurik's Cydia version 1.1.28.
But to be clear, the latest Cydia build from Jay Freeman is still in beta, specifically in beta 3, so there will be bugs and issues to be encountered, according to iDownloadBlog.com. The good news is Saurik has optimized Cydia for Todesco's Yalu jailbreak so it will be a better experience courtesy of the two jailbreak tools.
For those willing to take the plunge (be warned first that like the Yalu jailbreak, the latest Cydia version is not a walk in the park) iDB shared a guide for installing the jailbreak tweaks repository with the promise that jailbreak fans "may find this Cydia release improves their experience running the jailbreak slightly."
Now on the rumors that Apple has successfully patched its TSS servers to prevent the downgrade or upgrade to unsigned iOS version as facilitated by tihmstar's Prometheus. According to a separate report by iDB, Apple indeed has made changes on the TSS servers and it appears that chief design was to render Prometheus unusable.
Consequently, the move will also block the likelihood of jailbreaking with the help provided by the Yalu JB tool. Per a number of posts found on Reddit, this was the case.
Yet from tihmstar, Prometheus is still working. In an updated report by iDB: "tihmstar has stated that the tool is working perfectly, and that he has used it successfully multiple times today. The report, however, conceded that for some users the tool has been acting up since the changes implemented on the Apple TSS servers.
That being the situation now, iDB said that it looks like tihmstar is working on a fix to the issues pointed out by a number of Redditors. "Do not angrily delete your saved blobs in the belief that Prometheus will never work again, or do anything else rash like upgrade to iOS 10.2," the report recommended.
For now, it is clear that the Luca Todesco Yalu iOS 10 jailbreak remains the only working tool that jailbreak fans can count on and it is now slightly enhanced with Saurik's release of Cydia 1.1.28. And soon enough, tihmstar will fix the Prometheus issues in order to make the jailbreak experience a little smoother.