Did you ever find the battery?
Sounds like you found your battery connectors but no cables or battery.
Regarding being RV savy, I came up through the ranks as a mechanic, now I sell what I use to work on so I have a better than average mechanical aptitude, however, working on our RV has been somewhat of a frustrating affair for me. Most newer RV's have a fairly complex electrical system and it goes over my head often. I just finished chasing a generator issue, corroded hot wire from gen ECU to remote start switch, manufacturer was certain I had a bad ECU, cha ching, $wasted because the original ECU was still good, then there was the inverter issue. All modes of my new Xantrex 3000 watt charger/inverter worked except for the inverter mode. It took me a couple weeks in my spare time to finally figure this gremlin out. Turns out, the inverter was switched to 'search' mode. Turned search mode off and bingo, inverter powers up and works just fine now.
Don't be too hard on yourself and don't let some of the uneducated posters bother you about asking for help. Even the more seasoned RV owners have problems they can't figure out. Many of them simple take their rigs to a shop for repair because of either time or knowledge. Good luck with your new/old RV. In about a year you will be answering questions like you have posted here.