There are some potentially significant obstacles for your candidacy to a top program in the U.S. First, as you know, given that you come from an overrepresented demographic in the applicant pool, competition is quite fierce in terms of standardized test scores and GPAs. Second, I know the circumstances did not work in your favor, but your description of your job after university does not indicate that it would put you in the position to gain valuable leadership experience. I am not saying that your admission to a top 20 program is impossible, but I believe it could be difficult, unless you can differentiate yourself by speaking to your leadership experience both in and out of work. That could potentially differentiate you.
In terms of applying to another graduate program and then to an MBA, I think you would need to prove to admissions committees how exactly an MBA would enable you to pursue your career objectives in a way that your other graduate does not, which could bring into question why you even pursued the first graduate degree at all. That is a potentially tough and tricky sell.
I do not mean to discourage you from applying, but the factors you speak of seem to be challenging.
Best of luck,
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