Batteries not charging

[jola1925]

We just purchased a 2012 2027(QB). It came with 2 6v batteries, but they don't seem to hold a charge.
I have driven for at least 6 hrs, plugged it into my garage (30amp outlet) for at least 36 hrs & if I unplug from the house nothing electrical works, except for the jack.

The switch that shows how much battery, shows nothing. I don't understand electrical but I'm thinking I should take the batteries to be charged & see how long they last.

I'm including a picture of the batteries.

I also have a few questions , if anyone can answer.

1) Will a multimeter help see battery health?

2) should I consider a home charger, (Genius5)?

3) does anyone ever install LiFe batteries & not install solar? With maybe an eye towards future solar...my good eye too.

Thanks, jola