I have a Sony HCD-GS300AV bookshelf stero system. When I power it up affter about 3 seconds it shows an error on the display "push power protect".  There is no such button on the outside of the unit. The manual says nothing about it nor does Sony's website. If I push the stop,clear and display buttons at the same time it will run the demo program. I have located 3 fuses on the circuit board just above the cd carriage and they all seem to be fine. I will be greatly thankful for any help. Thanks.