Rubbing the display for 2 hours to push the liquid or whatever to the corner where it had "escaped" ?? whoo...!

I somehow feel that is not a very permanent fix; if it works at all it might well get back like it was or worse after some time.
(and might be dependent on the display type and blotch location, can it be done at all if the blot is not in the corner?)

As for doing that on N9, no way it can help, N9's got an OLED display which does not contain the liquid layer that the LCD of N950 has.
(And hence there can be no blotching on N9 screens AFAIK)