Q.jade plant
I have a mature jade plant I changed into a new pot and potting soil. My worry is I placed it outside in April on a very warm day. I went shopping, came back the leaves were burnt. I brought into the house, the burnt fall off and it started to grow new, but they also dried up. Now the big stems are going to mushy. How can I bring it back to life, very upset? Was going to replace it but very costly for the same size, also it means very much to me.

Certified GKH Gardening Expert
Make sure you did not use to large of a container. When repotting, only go up 1 size and make sure the pot has adequate drainage. The mushy stems could be from root rot. If healthy stems of the plant remain, you can prune these from the plants and propagate new ones. Here are some links with more information.
https://www.gardeningknowhow.com/houseplants/jade-plant/jade-plant-care.htm
https://www.gardeningknowhow.com/houseplants/jade-plant/black-spots-on-jade-plant.htm
https://www.gardeningknowhow.com/houseplants/jade-plant/pruning-jade-plants.htm
http://www.clemson.edu/extension/hgic/plants/indoor/foliage/hgic1507.html