Well, it's a long shot, but you might pull all the cables off the BCM and try a fuse - if it blows, you know it's not the BCM.

If it does NOT blow, it may or may not be the BCM, as with the connectors unplugged, a fuse that refuses to blow could indicate a bad BCM OR that one of the disconnected wires has the fault in it.

But, again, it's worth a try. Try pulling all the connectors off the BCM and see what you have.