I do get power to the board but when I press the on button nothing happens
Check manual - possible that you need to reconnect wiring. Start button is only a momentary switch which needs a 'power good' signal from the PSU. So the second issue is that the PSU may be failing.
To advise more would need lots of details about system and components. You may be better helped by troubleshooting adivce at http://www.computerhope.com/