I agree. Check the battery. Especially the water level as it can be charged but won't hold it under load if the water level is too low. Then try it all with a fully charged battery. If it is charged, there is no need to be hooked to shore power or a vehicle. I can cycle my slides in and out over a dozen times easily without recharging. But they are group 31 105 amp batteries.
And yes, there should be a big (fat) black wire going to ground and a big red wire coming off of the battery. But without seeing your set up and knowing if it goes directly to a battery switch or anything, I couldn't guess where the red one goes exactly. Mine I have going to the battery switch first, so everything, even the jacks you have to have the bat. switch on.
Probably your best bet is to have a good local mobile tech guy come out and look at it.
Good luck!