It depends if you have bud rot or powdery mildew.
If it is bud rot it will be soft and mushy, if this is the case bin it.
If it is powdery mildew which appears as a white powdery coating it can be treated and saved.
Here a vid of George Cervantes treating powdery mildew.
[video=youtube;S7jE7qzfgQs]https://www.youtube.com/watch?v=S7jE7qzfgQs[/video]
I had some bud which I forgot to burp whilst curing got some powdery mildew and I treated it and it was absolutely fine.
Here is a link to a thread to prevent and treat bud mold & fusarium which I originally got from mandala seeds.
It is a good read and worth a look follow the link bellow.
https://www.autoflower.org/f90/prevention-treatment-bud-mold-fusarium-36795.html