JEE

Your JEE Mains preparation of physics, chemistry, and maths is sufficient for IISER entrance examination but in additional to this you need to prepare biology because it is also included in the entrance examination of IISER. I would suggest you to solve some previous year questions before giving the entrance exam.

With a rank 21,000 in JEE Mains for the EWS category, you can get below NIT campuses:

1. NIT- Warangal
2. NIT Raipur
3. NIT Kurukshetra
4. NIT Surathkal
5. NIT Delhi
6. NIT Trichy
7. NIT Durgapur
8. NIT Puducherry

In all these campuses, there are various courses you can join including B.Tech CSE.

I hope it will help. 

Yes, it is possible to join a Bachelor of Technology (BTech) programme without appearing for the Joint Entrance Examination (JEE) in India. Many engineering colleges and universities have their own entrance exams or admission criteria for BTech programs. Some private colleges may also offer direct admission based on academic performance in qualifying exams.

Cutoffs for Computer Engineering increased every year from 2021 to 2023 - 4022 in 2021, 4307 in 2022, and 4558 in 2023. KJ Somaiya College of Engineering Cutoff for Electronics and Telecommunication Engineering increased every year with approximately 1000 ranks from 2021 to 2023 for the GOPENH category.

With a JEE Main rank of 218,000 in the EWS category, you have several options in Hyderabad for pursuing a B.Tech. It depends on in which branch you want to apply for. Here are list of some colleges that might be suitable for you

Jawaharlal Nehru Technological University (JNTU), Hyderabad
Anurag University, Hyderabad
AAR Mahaveer Engineering College, Keshavgiri
Vardhaman College of Engineering
Mahatma Gandhi Institute of Technology (MGIT)
CVR College of Engineering
Institute of Aeronautical Engineering (IARE)

Yes, Dr. Shyama Prasad Mukherjee International Institute of Information Technology accepts the JEE Main score for admission to B.Tech at Dr. Shyama Prasad Mukherjee International Institute of Information Technology, Naya Raipur. The candidate must have passed class 12th with a minimum of 75% aggregate in class 12th from any recognized board.

Don't worry if you couldn't clear JEE Mains. Here are the things you can do:

1. You can prepare again for JEE Mains and try next year. By taking the exam you have an idea of how questions are asked, your difficulty level, your strengths and your weaknesses, now you can prepare according to it.
2. You can also prepare yourself for CUET, for next year. Many central offer B.Tech courses based on CUET, for example, IP University, and Northcap University.
3. You can join colleges such as Greater Noida College, directly without JEE Mains.

I hope it will help. 

The minimum eligibility criteria for admission to DTU is 60% marks in the 12th board exam, with Physics, Chemistry and Mathematics as mandatory subjects. You meet this criteria. However, the final admission to DTU is based on the JEE Mains rank, not just the 12th marks. For the general category, meeting cutoff requires a JEE Mains rank within the top 4,500. For SC/ST candidates, the cutoff is slightly lower, but a rank of 106,645 in the SC category is still quite low.