How expensive the equipment is and the time it would take a technician to arrive, however short, are irrelevant.
It is usually only succeeds in worsening the problem, however, most techs appreciate the user trying at least some form of repair themselves. Hence, the rule.
Chalmers: What were you doing?
McCoy: Trying to make a call.
Chalmers: Then what did you do?
McCoy: Emergency repair procedure #1
Chalmers: You kicked it?
Chalmers: Well, at least you tried something.