With a 55% in your board exams, you can still apply for B.Tech in Computer Science, but your options may be limited in top colleges. Many reputed institutions require at least 60% for general admission, while others might accept lower percentages through entrance exams like JEE Main, CET, or state-specific exams. You can explore colleges with relaxed eligibility criteria, such as private institutions or certain government colleges, and check their cutoff details for a clearer idea.