thanks to all who responded, i really appreciate the help.
ok so to add clarity, here's what happened in my group.
My group found out about the Lost City of Omu very early in the game (like 3rd level). For those of you not running ToA, Omu is the gateway/location in which the group needs to find in order to get to the next part of the adventure, in which the book recommends you be at least level 5 before entering.
I wanted them to play around in Chult a bit more, so I made a bit of fluff up telling them that Omu was a hidden/lost city, and only accessed magically from the great ruined city of Mezro. I just wanted them to explore the jungle a bit more and level up, but i soon found out that the book had little info on Mezro and many locations had very sucky gameplay and almost nothing to do with the game.
So, i basically decided to put the garden of Nangalore in Mezro and made the medusa in Nangalore as my version of a "mini-boss" to beat before they can get access to Omu. So ultimately, they died fighting the Zalkore the medusa in Nangalore (that i relocated to Mezro), and therefore, they cannot get access to Omu since they didnt beat her and died in battle.
So now, they are starting new characters and essentially need to get to Mezro (Nangalore), but im wondering whether i should still keep the medusa there. Or should i just have them be able to get to Omu without beating her, and have her go elsewhere or be killed by another group like the Red Wizards (who are also looking for a cure for the Death Curse and are also in Omu).
if you didnt like that i relocated the Gardens of Nangalore in Mezro, let me know as well. Im good with constructive criticism.
let me know what you think!