I'm learning to fly with a DJI Phantom 1. At the same time, I'm attempting to build a Mini 250. I've purchased a Diatone PDB, v2.1, but am having some trouble understanding how to use it. First, is it meant to replace the bottom, or middle, plate on the 250? Most photos I have seen show it replacing the middle plate, but the LEDs that are included seem like they should be on the bottom so they can be seen. Secondly, the PDB comes with a packet of insulating washers. Are these meant to go between the arms and the PDB to prevent shorting? Are they needed anywhere else?