I would use Forever Black, available from CMA. Forever Black claims to be a dye, it can look good if applied right, and seems to hold up well.
I suggest you apply the product with a soft cloth. Use latex gloves so your hands don't change color.
The directions state to use the applicator. With the applicator or foam brushes, I could not apply the product without streaks. Cloth worked much better.
I would not wetsand, and do not think any of the Mequires cleaners would bring it back to black.
Lou