What you'd be on the lookout for is ammonia. I think you'd know if it was leaking. Smelly and dangerous.
Can't think of any reason that water on the floor and the fridge
not working would be related, but who knows.
will work off-level, so I'd think you'd at least notice some cooling, unless you're so off level that you can't even stand up in there. The problem is that it'll run off level, but will damage the fridge
. Definitely, in the future, never run the fridge when the camper is off level enough that you aren't comfortable hanging out/sleeping in there. The ammonia won't be able to circulate correctly in the coils on the back of the fridge, crystals will form and clog the passages.
I'm guessing that being off level isn't what's causing your fridge not to work, but you definitely want to level it before trying to run it any more.
What did the previous owner say about the fridge? Because if they said "I never used it so I don't know if it works", that's code for "it's broken"...99% of the time.
Did it come with the manual? It'll tell you trouble-shooting methods, where all the fuses are etc.