hi,

You have completed your diploma from Government Tool Room & Training Center, which is great, however from past years ISRO basically hiring for graduate engineers who have completed b.tech in computer science or mechanical or electronics and communication engineering or electrical engineering. however you must have competed b.tech to become eligible to apply for scientist b or engineer post. however time to time isro different branches has released recruitment to hire technician apprentice, so you should keep an eye on the career page of isro to get notifications about recent recruitment.

hope you understand.