One password, discovered over 20 years later, long after the Metroid password system had been completely reverse-engineered, does not grant you all items. This password just crashes and resets the game:
A Profanity-Laced Video Game Password That Breaks Everything | Max Woolf’s Blog
Most of these passwords were gibberish that required a pen-and-paper to write down and remember. One password, however, is more memorable, and much more sinister.
