The correction of your story:
When I was a teenager I did an electroelectronic course. In one of the practical lessons we had to fix an electric motor. The teacher made a strong recommendation that we should perform some tests before turning on the motor, but I ignored it. If I could do it again I would pay more attention on the teacher. My motor almost got burnt and I had to spend a week fixing the damage.
Augusto thank you very much for reminding me about the preposition.
I changed a bit the sentence where the verbs: advise and recommend are because I think in this way it sounds more simple and clear. I used the noun: recommendation.And the collocation : to make a strong recommendation.