Volume Control interfering with power button

I used my Casio LK-170 few days ago and ran perfectly fine. Just 2 days ago, it won't power on (with adaptor or batteries). During trouble shooting found out that the Volume Control need to be on high or the keyboard will not power on. Once powered on, and you lower the volume control, it creates buzzing noise from the speaker. Why would volume control have any affect on the unit turning on or off? and what is the remedy in this situation? Does the volume control needs to be replaced?