If you have a voltmeter, check the output of your main power supply. Assuming that is OK, check the voltage for each axis. Simply put your black lead on the incoming black wire screw and _carefully_ place the red lead on each test point in turn. The test points are fairly easy to find. Each is labeled 'tpt(drive letter)' and they are the only through holes on the board.
My guess is your main power supply is putting out enough to power the board but not the drive electronics.