M.Tech

I think the first thing you should ask yourself is:
"Are you still interested in engineering after 4 years of rigorous course? "
If your answer is yes, please start preparing for GATE. Another question for yourself, "Do you want to shift career paths? "
If your answer is yes, go for an MBA. For me, this worked well.
My suggestion:
India is a progressed nation. Our education system in terms of IITs and IIMs is well known to the world. I think, pursuing MBA/M.Tech from India's top institutions is equivalent and acceptable globally. Of course, exceptions exist. If you have that financial power in access, you can opt for foreign countries as well. Education abroad is a trend these days, but it's not as glamorous as it looks. Ask any of your friend or family member who lives abroad, what they go through, and then decide accordingly.

Many things can be done after B.Tech and M.Tech but that many things depend upon what option you will choose in order to pursue your further education. So, let's take the first case, you have done your B.Tech in mechanical engineering and you have done it from a university then you could have got good campuses and good knowledge too. And later on, you have opted for your favourite course in mechanical engineering. This is the best part. Now, I was telling you about other cases.
001. You can appear for many governments. exams and State Central Board Exams (Bachelor Qualification).
002. You can appear for GATE and plan your career.
003. You can approach various campuses and get placed in which stream you are willing for.