Our cable TV boxes are also warm all of the time and I utilize mine often. A cold turtle will not and should not eat. They cannot digest their food when they are cold. Visit your local garden nursery for other soil heating ideas. It s best to leave the overhead light off at night so the turtles become accustomed to the difference between day and night.
All box turtles are prone to swollen eyes which is said to be due to a Vitamin A deficiency.
Recently information has come through stating that it really helps if you drop the Vitamin A right onto the eyes. I ve tried it and it works. Water should be up to the turtle s nose, no deeper. Drop A Day multivitamins for birds by Geisler is a good water-soluble solution. Enjoy your little babies.