Everything is explained there. Not posible directly but in QA section it is clearly explained how-to
Why should somebody waste time to copy/paste what is already explanied there and hundreds of other users were able to find it, understand it and apply it. And if they had particular probem, then that particular problem was responded by experts to them. So, isn"it better for you to rely on that, or you want that somebody give you here too short/un-precise/wrong answer and you brick your phone?!
It’s safe to upgrade with method 1 . I’am afraid to use method 1 with change id.
In the past i used meizu m2 and i brick ( i upgraded 126.96.36.199 A beta from 188.8.131.52 A ) and after i decided to downgrade without clear data… i checked just upgrade firmware).
My phone dead(hard brick) because i have not checked ‘‘clear data’’?
Time ago I’ve changed the ID by method 1, it was fairly easy and straightforward.
Generally, not cleaning Data should not brick the phone but may cause particular apps to malfunction. But who knows, you say you were downgrading from Flyme 5 to Flyme 4.
Btw, there are also some topics under Q/A or Modding about changing/fixing Recovery (if that’s your hard-brick issue)