Computer Science and Engineering

They won't entertain your percentage. At least, 70% is required to study in Canada.

Hello Siddharth,
If you are about to opt for CSE branch of engineering, then you already must have cleared the required entrance exam. In that case you need to do nothing. Just wait for college to open.

You can go for Diploma in computer engineering after 10th or you can go for BE in CS or IT after 12th with science. You can also to BCS after 12th.

IIT Chennai is the best institute for B.Tech CSE in state of Tamil Nadu. You may refer to ranking of top CSE colleges in state of Tamil Nadu:
https://www.shiksha.com/b-tech/ranking/top-computer-science-engineering-colleges-in-tamil-nadu/46-2-123-0-0

Everything seems easy if you have interest and determination to work hard, engineering is not as easy as it sounds you need to work very hard and maintain good overall GPA to get placed, but if you want to take one branch out of it then CSE will be best considering your requirements.

No, he cannot get any NITs, IIITs or GFTIs. So he can try any colleges that admit based on both JEE main scores and board exam scores.
You can browse the list of colleges that accept both these parameters for admission.

Hello Vimal,
You have got only 85 marks out of possible 360. What went wrong? Can you do analysis? Failure is foundation of success. If you over come defects and study with full vigour, you may clear JEE Mains next year with 200+ marks.
This year there is no chance.