To reset the Sony receiver to demo mode, unplug the leads to the front panel. An alternative would be to unplug the power for 10-15 minutes which should reset everything. Best solution would be to check the manual for a way to restore to factory settings. (Also known as 'factory reset')
you can reset to demo mode by unplugging leads to front panel, once problem is located you can clip the problem leads loose to gain use of the unit again, this will cause loss of the problem area, but you will regain use of all other features to the unit again.
Press "Guide" and then the "Down Arrow" buttons, in that sequence. If that doesn't work, you cam try simply unplugging the item from it's power source for a minimum of thirty minutes. This will give ample time for the internal computer to reset itself and usually return to normal function.
If the Sony receiver freezes, or simply isn't acting properly the easiest thing to do first is to reset the receiver. Simply press and hold both the 'guide' and 'down arrow' button at the same time. Both these buttons are located on the front right hand side of the receiver.
track the problem by opening the case and start unplugging leads until the unit restarts without protection signal, you can reset to demo mode by unplugging leads to front panel, once problem is located you can clip the problem leads loose to gain use of the unit again, this will cause loss of the problem area.