Hello aspirant,
Candidates for B. Tech for Diploma Holders must have successfully completed a 3-year diploma in any engineering stream. These diploma holders are eligible for second-year engineering entrance. Because of this, they have an advantage of one year and can complete the course in three years.

Through national or state-level entrance exams, students who want to pursue a B. Tech after Polytechnic can enrol in B Tech programmes. Students must show up for the JEE exam or other state-level exams.

You will be admitted directly into the second year of engineering if you apply for admission after receiving your diploma. Your performance in the Diploma Engineering will determine if you are admitted to the second year of engineering, per UGC and AICTE regulations.

For more information,
https://www.careers360.com/courses/b-tech-bachelor-of-technology

I hope this information is helpful. Feel free to ask any additional questions.

Firstly you should complete your diploma in engineering course and after that you can take  directly admission in 2nd year of BTECH