Clarion cd, tape, radio all in one from Nissan - no sound?

It's a Clarion cd, tape and radio all in one. The model is PP-2371H. mine doesn't seem to need a code, the Cd plays for example.. But there is no sound coming from the speaker(s) - as it is second hand, if someone overloaded it, what would be 'broken' on the circuit board? one or two components? or something more? i measured 0.07V coming out to the speakers which seems too low(?) Any help in fixing this would be appreciated!