Yamaha psr-970 keyboard no sound and display issue

1) My psr970 Yamaha keyboard has an audio problem no sound at all the case is on main(mother) bord . The audio ic on the board are normall physically but no voice. what can I do?

2) an other one is not displaying full massage on screen, it's blinking and returning back and again blinking then again returning back. It's also on mother board so what can I do?