An "alarm" could be a bunch of things, but doesn't sound like it is related to your other woes. Maybe a leveling jack not registering its "stowed" position, or a sensor for the roof antenna, or LP gas detector or...
Turn signal is often just a defective bulb on a front or rear turn light, but might laos be the switch itself (the one on the steering column).
Which batteries are dead, house or chassis? When driving, or while camped somewhere.
2004 American Tradition; 2013 Buick Verano
Homebase in the Ocala Nat'l Forest near Ocala, FL