How do I fix black roots and get an even dark blonde at home?

My hair was like a yellow blonde and I dyed it dark blonde. It did get dark blonde but the roots stayed black. Do I need bye another box and dye the roots again, if so for how many minutes? Do I need go to a salon? I left the dye on my hair for 30 min and just the middle and bottom got dark blonde but the roots stayed black. I don’t want go to a salon as hair salons never dye my hair correctly and all suck. I’m traumatized.

How do I fix black roots and get an even dark blonde at home?
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