I've cleaned out my OR mini, and reassembled the board set (which might not even work, due to acid damage) but there are two connectors that are not keyed and could go on to the board in either orientation.
One is the small 3-pin connector, the other is the main edge connector. Could you post a photo of that connector? Since it's got an 'L' shape to it, I could know how to put it on based on which direction the L faces...
For the 3-prong one... not so easy. I'll have to trace back the wires (I'm guessing it's power)