No power from battery to camper

Probably tripped the small resettable circuit breaker, tucked up along the A-frame.
Has a tiny black reset button you have to push.
Usually trips when battery gets connected backwards.

Would the previous owner have a clue?

The circuit breaker most likely has no button to push as most are auto-resetting.

With a voltmeter, trace from the battery all the way to the panel inside to see where the voltage is lost. Easy to do.

There are two kinds of main breakers used. One is the self resetting kind
The other had both a button and a lever.. I ... had issues understanding it the first time I saw one.

An automotive test light. this is a tool that looks like an ice pick with a light in the handle and a wire coming out the side of the handle.

Hook clip to battery negative touch tip to battery positive BRIGHT good. no light make sure the bulb is properly set (I often have to reset)

Move clip to any non painted metal frame part. Same. only now you are testing the battery negative cable (likely good) and connections and the attachment point (I say likely good cause jacks work)

Now move out along the battery positive lead. Every time you find a connection test.. You may have to move the ground clip as you go.

Retest last known GOOD point if you have to move the clip (Testing ground clip)

Broblem exists between BRIGHT and Dark.

You can also use a volt meter. But this is so much faster and easier to read.

Some RVs have a 12 volt disconnect switch somewhere inside.. Mine was at foot level in the step well, I would hit with my foot, then no 12 volt. Sometimes it is an easy fix once you find the switch. Hoping it is something easy!!

Some RVs have a 12 volt disconnect switch somewhere inside. Mine was at foot level in the step well, I would hit with my foot, then no 12 volt. Sometimes it is an easy fix once you find the switch. Hoping it is something easy!!

If the battery is/was connected with reverse polarity it would have blown the reverse polarity fuses. These are likely near the other 12v fuses and the converter.

Get a meter (even a free-with-purchase-and-coupon Harbor Freight one), and track it down, step by step. Anything else is just shooting in the dark.

Reset button is really really small on some of those circuit breakers so look and feel really careful! Good luck.

Here’s a resetable breaker like the previous answers have referred to. The small black button on the side resets it. Mine is inside a metal junction box where the 7 pin cable connects to the TT wiring. Resettable Breaker