Beeps + No Boot-up

My 2 Yr old Celeron PC powers-up immediately power is turned on, without pressing ON button – I hear ONE extended BEEP – Soon after I get continuous BEEPS until I press power button to turn OFF – No activity on monitor. I have tried swopping PSU + RAM + Graphics Card + CMOS Battery. I also tried clearing CMOS Jumper (JBIOS). Does it mean Motherboard failure? Any suggestions appreciated. Thank you.