If these are ok,check to see if there is an external fuse on the back of the unit. If not, DO NOT OPEN the case as dangerous voltages are present inside the set. The internal power supply may be burnt out ,so send the unit in for service. If the unit lights up but you get no sound ,look to see if the speaker selector is switched to the speaker output you are using. Sometimes a small indicator light or symbol will be seen on the display.
Most units have a protection relay that clicks on a few seconds after the unit is powered up.
If you do not hear this click or the protect indicator stays on , there is a good chance the output stage is shorted in the unit. Also check that the speaker wires have not been pulled out of the rear of the unit or out of the speakers. Static,noise and loss of signal can be caused by loose or defective cables .move the RCA cables with the volume turned low and see if you get static or signal dropout. If you do try cleaning the jacks on the rear of the unit or replace the defective cables. If you have static when you move controls and switches they may have to be cleaned.