Check the board the fan is wired to. I believe the shut off is associated with the amp being cool. If there is a problem, it will not shut down. I just pulled mine apart to install a new fan. When I tried to power it down, it would not go off. Replaced the fan, cleaned the amp, wiggled components on the boards for the fan and power, it now shuts off. Did you get those amps from the guy in Philly?