Test your magnesium. High magnesium has been connected to a snails muscle contractability. I don't have studies on that though, just something I heard and experienced.
Your margarita snails are a cold water snail.... pretty sure your tank in warm. Sometimes they can tough out a warm tank for awhile... sometimes not so much. Depends on the number and severity of insults received during collection, multiple tank changes, horrible holding containers, etc, etc. Snails get treated the WORST of any of the shipments. Coral gets treated better. But at any rate, they generally need cooler temperatures than we provide.
And I'm not being cranky about this, but I am being preachy. It's not the snails fault we put them in an inappropriate environment. Some snails are sand/rubble snails, like the Astraea. They do not even have the righting mechanism to turn themselves over... it's not in their biology. So we take them from their appropriate environment that evolution decided to make them perfect for, throw them in a tank they are not suited for, complain when they can't right themselves because they are physically unable to, and then leave them there to die because they don't do what we want them to!! That's just.... not nice. I keep Astraea in all 12 of my tanks. I turn them in the morning when the lights come on and then when I feed at night. I do not keep hermits and Astraea in the same tank. I've had the same 13 Astraea in a 24 gallon for 3 years now. If I can do it with all of my tanks.........
Turbos are in a mixture of temperatures. Sometimes you'll wind up with cold water, sometimes warm depending on what variety comes under the loose common name. I have kept them all and I find the orange ones to be very hardy and active.