Thank you but sadly, the reality is she's likely suffered from hypothermia and has passed or is not able to travel to get to lower ground. The past two nights have dropped to the forties and it's now raining ...I hope her suffering is short because I'm responsible for her and I'm feeling pretty lowly right now.
Those temps aren't likely to kill her. Especially if it warms up and gets sunny the next day. Rain doesn't help, but it is by no means a death sentence. Don't give up. Keep looking. They tend to dig in to the bases of bushes and stuff. Sometimes it helps to get down on your hands and knees and see things from a tortoises perspective.