I now have the "Revolution Mini" and oplink-air. The sensors are on the bottom of the board (side the connectors are not on) but the board is in the case flipped so the sensors are on top. It's normal board rotation when mounted upright and with the arrow pointing forward is roll=0, pitch=0, yaw=0. An interesting note: if the config loaded in the board has the oplink configured it won't boot without it connected.
I loaded your 1624board.uav file and saved it to my board. As you say, the PFD is really out of whack.
I then changed to roll=0, pitch=0, yaw=0. This was better but there were still problems. As Laurent mentioned a few messages back the BoardLevelTrim settings were wrong. I reset both to zero, did a save, watched as the PFD went into a continuous spin, unplugged the board, plugged it back in, and the PFD works normally.
I've attached a corrected copy of your 1624board.uav file named forDave201603241233.uav. Try loading it to the board and power cycling it. I have no way of testing what it does to the heli but the PFD works normally. It assumes the board is mounted as you said it was last, top up and arrow pointing forward.