Help fixing staining/ stripping disaster

Hi,

I have an old somewhat worn, but sturdy deck. I used a Home Depot brand stripper. For various reasons I could not use the brightener right away, and did this two days later. However, it did not work, there are still some dark black spots throughout the wood. I am planning on sanding, but I'm not sure how much that will remove. My question is will a solid stain cover the dark black spots, or will they still be visible. My understanding is that a solid stain acts more like paint. Any advice would be greatly appreciated!