Diploma

If your college is good enough to provide you a better placement, then don't look for another course, because one year or two year experience is far better than your new course. If you don't get placed, then I will suggest that you must do M.Tech in VLSI domain, or whatever you want. I said M.Tech because moving from technical field to non-technical is easy, but you have worked for 4 years on same thing then why will you go for MBA or other courses. Don't be a path follower always be a path creator. So, choose whatever you want. Or else
For your career it will be better to do B.Tech or do apprentices in any government organization and to improve skills and command on ECE application you join ESTC MSME training center. There are different courses in these centers.

TCS does not allow anyone who have percentage below 60% in class 12th. It is clearly mentioned in TCS recruitment policy, but what if I tell you there is a way out (for people in the range of 57%-60%).
You give the recruitment test filling your details as 60%. You get through the selection procedure. You get the offer letter. (Before this stage no document verification is done).
You solve aspire modules. You get joining letter and you ILP location. If you have your ILP location other than Trivandrum, there is a possibility you can get through. I have seen people in the percentage range 57%-60% getting through TCS recruitment procedure and are currently in TCS's payroll. It all depends on your luck and the person verifying your document. So, I would say if you don't have any other opportunity, give it a shot, you never know what Life has kept for you.
All the best.