We did several power cycles -- kept hoping we could fix it ourselves without waiting 48 hours (we were leaving in 24). The last time the modem went out (January), Embarq accidentally they sent us two. The unopened one didn't work either.
Power cycles are useful in a lot of situations. A student of mine was giving his senior seminar and needed the LCD projector to display his PowerPoint presentation. The projector cable was physically connected to his laptop, but the display said no signal. I told him to do a power cycle, and voil?! It worked.