it looks like something shorted the bottom of the posts. I know that they used to put an alloy plate covered in stiky stuff inbetween the boards, but now they only put a small pice of fiberglass(?) that can brake off easly, mabey that broke loose??
It looks like you might have a cold solder issue. I don't know if anyone noticed in the close up pic, but I see there isn't enough solder on the wires and that might have caused the problem. I tin the crap out of my wires to make sure it will always have a strong bond after I'm done soldering.