I've a low score of 47% for Btech(ECE) from Mumbai university. Do I've any chance for Mtech in any decent clg other than IIT/NIT? If yes,what central and other state exams(since I'm from Maharashtra) should I look for?
See most of the entrances claims a minimum marks of 50% for UR and 45% for SC/ST. Thus unless you are SC/ST, the possibility of getting eligible is less.
If you are SC/ ST then you are eligible for TANCET, AP-PGCET.
I would recommend you to reappear on some of your papers if possible and increase your aggregate so that the threshold of 50-55% be crossed.
To know about MTech entrance examination in India you can visit the link below:
https://engineering.careers360.com/articles/mtech-entrance-exams
I hope this answer helps. All the very best for your future endeavors!