What happens if you put blonde dye on top of black dye?

I just bleached my hair from natural dark black (1B) to a sort of ombré'd light blonde. It came out nice but was a little brassy so I toned it with Wella Color Charm in T18 (blue based) I guess within three minutes it was over toned -___- I was pissed! It's now a really ash blonde. I also got the bleach too close to my roots in the front so i bought a 1B hair dye to touch up my roots. I did it in a way that my roots would fade into the blonde. Problem: now that part where my roots fade is a subtle greenish grey. And I think when rinsing out the black dye it kindle got on the ends so now my already ashy blonde is even more lifeless at the top. So I'm thinking: what happens if I buy a brighter blonde dye to put all over the ashy blonde? And I also put it on the parts where the black fades to blonde? Will the black stay black, or will it lighten to orange or something? And if so, should I use a rinse/semi-permanent blonde to brighten things up? Please Help

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