Ok, I might have been too vague in my question, sorry Plinkie.
Well, the yellow icon is the power source. If you connect a red square by putting it next to the power source it will get powered indicated by turning green. (This is my problem ->) If you have a string of (cords pieces) red blocks (that is now turned green) and removes one block in the middle of the string - the rest of the blocks that are not connected to the yellow power generator will lose power and will turn red again.
The tilemap is a work in progress and needs a bit more explanation.
I hope it makes more sense with these pictures. (English is not my main language.)