Overload is displayed even when I disconnect all but the power. When I push Power it reads 'Tuner' for a second, then go blank and the word 'overload' scrolls across the screen. Overload will keep scrolling until a button is pressed. Once you press a button the screen will read 'Switch off Power'. How do I fix this? Or is there a way to reset the receiver? Thank you in advance for your time and help!