Touching the heating element in the window is NOT the problem. The problem can be the electrical box at the base of the window.
Next time you're in the cockpit lean forward and look at the base of the window just forward of the respective lighting control panel. There's a connection box there with two caps on it. Both caps must be in place and not damaged. Throwing stuff on the glareshield can damage the caps.
I believe the box is black with grey(gray) caps that are about the size of your fingernails.