If you’re looking to pursue a B.Tech in Computer Science (CSE) in Chennai and can’t take entrance exams like JEE due to health issues, there are still good options for you. Since you've scored 81.5% in HSC with a cutoff around 140, you can apply directly to some private engineering colleges that admit students based on their Class 12 marks. Colleges like SRM Institute of Science and Technology, Sathyabama Institute of Science and Technology, Hindustan Institute of Technology and Science, Saveetha Engineering College, and Vel Tech University often offer direct admission or conduct counselling sessions based on board exam results. Just check their official websites for detailed admission steps, and make sure to have all your documents ready, like your marksheet, transfer certificate, and medical certificate if required. It’s best to apply early, as these colleges tend to fill up fast.