might take your microcontroller out, power up the OSboard and test that there is power on the other side of the triacs, if so it could be a signaling problem.. Check the Pi next all by its self and make sure its outputting a signal on the GPIO pins for the OpenSprinkler.
If you got no power on the other side of the triac then keep trying to trace it further up the schematics to see if there is a bad component on your OSBoard