Hello Deep, 

Your question is very confusing, Btech and Polytechnic are two very different courses, where Btech is a degree course which js of 4 year duration. On the other hand Polytechnic is a 2 year diploma course in engineering. So you can not do Btech in Polytechnic.

I request you to please clarify your question once.

Hope this helps, Thank You 

All the best