Once it's up, you could pull the fuse to keep it from operating more (assuming you have a fuse and not, say, a self-resetting circuit breaker).
A bad ground is a reasonable guess for the cause of any bizarre 12V electrical problem that seems to defy common sense explanation. A loose wire on one of the activation switches may be another explanation, but I'd check the grounds first. If you don't have a fuse to pull while working on it, you can disconnect the appropriate battery to ensure it doesn't have power (often that's the chassis battery, but not always).