What Murphsmom said.
Also, the slide and jack are connected to the battery through separate auto resetting breakers. They don't go through the fuse box. The battery disconnect should only disconnect the fuse box.
The main line to the fuse box may also have a resettable breaker or fuse, but I'd check the battery disconnect. If you don't have a battery disconnect, then the resettable breaker has a problem or the wire from the battery to the fuse box is open.
Since you don't have 12V power when disconnected from shore power, you also aren't charging the battery.