As long as the battery is connected and fully charged, all 12 volt lights & accessories should work.
If the electric tongue jack works, but nothing else, check the Breaker near rhe "A" frame. The breaker will look like the image below. It's possible there is a bad connection or the breaker is Tripped or went bad. Some breakers have s Manual Reset
button. If so, press the button and it should start working again. If it's a Auto Reset
, it will need to be replaced if it doesn't automatically reset.
Below is a Manual Reset Breaker. Note the small black button on the side.
Below is a Auto Reset breaker.
These are generally located near the A-frame tongue. Look under the front of your trailer behind the tongue.