This ended up happening on a second board, it happened after upgrading to the latest firmware and my button was sticking a little, and eventually the fuse blew again. I just received in the fuses my SMT soldering skills are horrible but I managed to get the fuse in place. After testing both boards, when the battery is plugged in as an atomizer is attached it will auto fire, both of them act the same way. Can a low lipo charge cause the switch be stay open somehow?