Check the inline fuse located on the main power supply to the unit. If it is blown, replace it with a 1 amp, normal blow fuse. Clean all corrosion from the fuse housing, and replace the fuse holder assembly if necessary.B) Check the power cable connection. Be sure that the unit is connected to a known power source : Red wire to positive , Black to negative or ground.C) Ensure that the power source is powered using a test light, or some othe reliable form of testing 12-volt power. D) If you are sure that the unit is receiving power and is still not turning on, please contact customer service.