It looks like the 24V power (assuming the batteries were connected in series as were your old 6-volt ones) wiped out the electronic ballast units in your Florescent lights. These units take the 12VDC and internally convert it to a much higher voltage (apx 110v AC) to light up the FL tubes.
You might contact Thinlite (or whomever was the mfgr) and see if you can get replacements.
Otherwise it looks like you need to go get a couple of new FL units.
Sometimes you can fnd these at some of the RV surplus places, but my guess is that your chances are kind of slim.
RVA Dave is our resident technical guru, so hopefully he will drop in and provide better advice.