Here are some examples:
* Correct: The technician fixed the computer.
* Correct: I am a technician.
* Correct: The Technician Training Institute offers various courses.
The only time you would capitalize "technician" is if it's part of a specific title or name, such as:
* Correct: The Chief Technician was on duty.
* Correct: The Technician's Assistant helped with the project.