Waste of time. none of the top firms care about random certificates.They recruit people, broadly speaking, in two ways:1) From undergrad or postgrad top-ranked institutions2) People with relevant experience of use to them, eg doctors, people from the likes of P&G and other blue-chip companiesIt seems that you, unfortunately, fit neither of these.Going back to business school would theoretically make sense, and your work experience to date would suggest that it would give you the leg up you need to have a shot. Except you have an MBA already and so I would imagine that all of the top schools would have some significant concerns with your application. Certainly I would if I was interviewing you for my B-school.The other option, to gain more (relevant) experience, would also make sense, but I don't know how you go about getting it from where you are now.Maybe you should try both routes and see what you end up with. I would definitely have a plan B and a plan C though, as it may well be that it doesn't work out for you as you would like. Not everyone can work for BCG.