Just bought first camper - lot of questions - can you help?

Get solar, it will be the best way to enjoy your new trailer. You won't be sitting in the dark, bored, because you're being a battery miser.

I would bet that the battery that came with the trailer is now deceased or at the best, terminal. Put a new battery on your shopping list. Read the 12 volt link supplied above. Also, either disconnect the battery when leaving or install a disconnect switch (unless you get solar).