Stiff Back Legs

Yesterday because of Hurricane Irma knocking out our power we brought my bearded dragon outside in a small cage. I think we left her out there too long and when we went to bring her in her back legs were stiff and her mouth was wide open. Also her front legs are very weak. We tried soaking her in a warm bath mixed with some gatorade to try to hydrate her. Later we gave her another warm bath. She's showing no improvement and we don't even know what's wrong. Please help!!
U pdate: She's actually starting to move her back legs but very weakly. Her eyes are bright but her body is weak. We're going to take her to a friends house so that she can have heat. What else should we do??

I'm sorry to hear this! The open mouth usually indicates that they are too warm, and are releasing excess heat. It is the way they regulate their body temperature from becoming too hot. Weak and/or stiff legs can be a sign of MBD. How long has she been without any UV light?

Did you have her in a glass or clear plastic container that wasn't open and in direct sunlight? If so she has heat exhaustion/heat stroke and needs ORAL HYDRATION, NOT BATHS! No more warm baths unless she actively drinks in the tub, as they only get hydration if they take fluids in through their mouths! Warm water is the opposite of what you want to do, you're only heating him more, and pouring Gatorade in the bath water does absolutely no good at all, they absorb no hydration through their vents or skin.

Please go buy some Pedialyte only (NO GATORADE OR POWERADE, FULL OF SUGAR AND BAD FOR HIM), and start dripping the Pedialyte on his snout with an eyedropper or oral syringe and let him drink it. This is imperative as he's severely dehydrated right now, and probably has some neurological damage from the heat stroke, he needs oral fluids. An experienced reptile vet is the best thing you can do, they'll give subcutaneous fluid injections.