Fortunately with some fixtures, the PC hole isn't over the ballast. I think the Power doors won't do that well though. Especially the ones without holes on the ballast door.
even if the ballast isn't mounted right under the PC socket if water gets in the hole it's going to fry. All of my lights except the OVC have the ballast close enough to the PC socket so that if the hole was left open rain would get to the ballast. With the OVC it could probably still get to it. I think with the OVC the water would just drip down the reflector and probably get on the socket or work it's way into the optical area and collect in the refractor.
I think the gulls may have pulled it off somehow