Had a kicker amp go bad on one of my friends. When he turns his stereo on the protection light will come on and every 5 seconds the power light will come on for an instant and his subs will make a thump sound. His amp is the KX 300/4 and is a refurb. He bought it used so i told him maybe the same thing went bad on it again. I also told him to call up Kicker and agive them the serial number and see if they could tell him what had went wrong with it originaly and if it was even worth to send it back in to get it fixed. Do any of you guys have an idea of what else may have happend?