A few users have reported electrical shorts in their wiring with the QAV500 Power Distribution Board. When the surface of the PDB is scratched it is possible for copper to show through. If both sides of the mask are scratched a short can happen. To prevent this issue from happening, we suggest to place nylon washers under the screw heads of the screws that are holding the arms and spacers. See the below picture which points out the placement of the washers for the arm screws, but again, we suggest to place washers under all the screw heads on the same side.
We are also in the process to manufacture re-designed PDBs that will eliminate the risk of these electrical shorts. The new PDB will be available in 2-4 weeks and we will make it available to existing customers that would like to upgrade their PDB at a reduced rate.