I observe that a mezuzah is attached to the door with the top of the mezuzah directed to the top of the door.
I am looking for sources to answer this question:
If a mezuzah were (accidentally) attached with the top of the mezuzah facing down, has the mitzvah been fulfilled? Would a new brocho be required when putting it back the right way up?
Related: Is there any restriction on what constitutes a mezuzah case?