AsNoriuanswered grow question 3 years ago She is very close to beeing dead, by colour looks like she is in huge trouble. I doubt she will make it, or you will nurse her two weeks while she will return ...
Better start new.
That necrosis and such yellowish pale worries me a lot, your soil I humid too, but I never seen anything such rapid and only to one and I had many mistakes ...
Mold, mildew, fungus ???
Good luck !