How frozen were they?
A thin layer of ice on top of liquid, NOT extending down into the plates..
no problem, re-charge, and you may wish to equlize.
Ice extending into the plate area.
read all of this...
Do this part in either case: Get a small can (Testors brand?) Of red spray paint and paint the POSITIVE wires while they are still connected,,,, Optionally use BLACK on the negative wires.
Take pictures, of the batteries as connected, showing the connections.
Now the rest: IF the ice excends down into the plates...
let paint dry, remove batteries for replacement, and get new ones.