Casio AP-650M no sound

Hi Guys, cannot download Casio AP-650M repair manual, the Site says I have ad blocker and cannot find where to switch it off. Even installed new browser and the same result. My piano has no sound output other than to headphones. I am planning to start checking with phone jacks if the stuck in phone position, then will check amplifier but there are too many screws on the bottom, not sure how to open the board for not unscrewing and dropping inside parts by removing wrong screws. Can someone help with and advise or link for service/repair manual? Thank you