Whoa.. 110*F is WAY too hot.. It should be 90*F on the warm end and about 78*F on the cool end.. Also, you didn't answer the question about where the gecko came from and whether the others came from the same place or not. The hot temperature can turn the gecko off from wanting to be active, not to mention it used to be on sand.. I think the problem here is one of two things(Or both..)
1)You failed to do proper research before buying a Leopard Gecko(I'm not trying to be mean, it's just a very common mistake..)
or
2)The place your gecko(s) came from are carrying animals that are loaded with internal parasites.
If your gecko won't even respond when you put him/her on their back.. That's a very bad sign and it probably won't live much longer.. Remember 90*F on the warm end and 78*F on the cool end.. Over heating kills just as badly as not enough heat, so seriously.. Be very, very careful.
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-Britney
2.4.1 Leopard Geckos: Ron, Raine, Dream, Tango, Go-Go, Johnneh and Salleh.
0.0.1 Bearded Dragon: Lil' Little.