please clear CMOS by shorting for a few seconds pins of CLR_CMOS
if still no help then disconnect vga, hdd, optical drive, memory from MB, just leave only CPU and PSU. then check if there is any sound from speaker connected to F_PANEL pin header when power switch on. if no sound it maybe failure of PSU / MB / CPU, then you will need to exchange each one of these 3 components to find out which one is damaged.