It is simple, they give the sequences and what actions are deployed during the upgrade, they also gives the kind of error codes you may stumble on for each sequence. From this you can pinpoint where the problem is ; in addition in the article , they gives you infos on the cause of the error and how to remedy it.
This will not fix the upgrade issues. It will just help you identify the area of the problem and also not trash the system. Pretty good step but they should also focus on their updates not being crap and buggy for half the users.