Has it worked before in this scenario? How is it connected?

Here's the bad news.  I purchased it off ebay with intent of connecting to my AV7000.  When I first got it, I just plugged it in to see if it lit up.  It did.  Now it doesn't.  I checked the connection to the BM 4500 with my othe MCL 2p and the connection worked for that one.  So I don't think I had it connected wrong.  I took it apart and did notice some leakage out of the larger rectangular black plastic box on the left pc board.   I'm not sure what this componet is.  It certatanly does not look like a capacitor.

can you post a photo of the area that is affected and the leaking component ?

If the black rectangle to which you refer is 2.5" x 1.75" and the stuff leaking out is white then it is normal.  The device is a power amplifier integrated circuit and the white stuff is heatsink compound.

Unfortunately there is no service manual for the MCL2P on the site so further help is a little tricky...