I think I know what you’re referring to.
In 1875 Swiss-American geologist Jules Marcou advanced a theory that the name America comes from the Amerrique Mountains in Nicaragua. The problem with Marcou’s theory is that the name Amerrique isn’t attested before 1874. English geographer Thomas Belt wrote a book on American geography that year and used the name. Marcou read it and based his theory on that. The problem is, that no one had heard the name before Belt recorded it in his book. No one took Marcou seriously, not even Belt, who couldn’t identify where he’d gotten the name from. But Marcou continued to tout his theory and it eventually caught on in some fringe circles. But it is pretty obvious that the mountains were named for America sometime in the nineteenth century and not vice versa. (Allen Walker Read. “The Claims for a Native Source of of the Name America.” America—Naming the Country and Its People. Lewiston, NY: Edwin Mellon Press. 2001)
America is absolutely, positively named after Amerigo Vespucci. Seldom in etymology do we have such absolutely clear evidence as we do for this fact. In this case, we’ve got the testimony of Martin Waldseemueller, the man who coined the name in 1507, explaining exactly why he named the new continents after Vespucci.
But if you’ve got actual evidence that America is not named for Vespucci, please present it. If it’s for real, there are any number of peer-reviewed journals that would be salivating over the chance to publish it. You’d be famous. (I’d like to promise you wealth and riches, too. But this is the word business. A small modicum of fame is all we have to offer.)