Who to believe?

Purchased a new 17 foot travel trailer in August 2017. Had it delivered to a relative's house while I was away until last week. The first thing I noticed upon closer inspection of my new purchase was that both the tires and the front hitch assembly were "Made in China". What isn't, right? Opened the door for the first time, climbed in (this is now February, 2018) and none of the lights would work.

I pulled out the new "deep cycle" battery that was in a plastic (of course) box on the front/outside of the trailer (green top "Interstate" brand with semi-transparent walls). I could see the acid level through the sides of the battery and all the cells seemed to be OK, fluid wise.

Took the battery down to a recently opened O'Reilly auto parts store for a re-charge. The clerk guy called me to the back of the store before I could leave. He had hooked up some cables to the battery, pointed to some kind of meter, and told me the battery was shorted-out, defective, no-good (I don't remember his exact words). I aborted the idea of a re-charge when he told me I would need a another battery. I left with the battery in hand.

Dropped the new battery off with the salesperson who sold me the travel trailer. The service department was closed on Sundays. He said the service department would call me the next day. Of course, no one called me, so I called them. The gentleman in the service department told me they were going to charge the battery all day and get back to me.

The following day, the service dept. did call me, and told me to pick up my battery, nothing wrong with it. But now I left town again, and won't be back for who knows how many more months. They will have to hold onto it for me. Just wonder why the two businesses (O'Reilly and the Travel Center) had differing opinions on the condition of the battery?