I think that's what you've been trying to figure out and you're seeing how long it is taking to even find it out, let alone fix it. When a drive becomes maimed to the point of not even being able to give error messages, there's not a lot of hope left for a repair. And, even if you did eventually figure it out and get it to boot, you don't know what else you have corrupted that could later lead to more problems.
I've been down this road of wanting a solution, and trying many, at any cost, and I've lost important data because of it. I can only advise that you don't do the same and concede to the fact that sometimes you're just not going to have an answer to what or why things happened at such a low level corruption like this, unless you have a lot of time and energy to spend pursuing it (which you might).