I purchased a jade plant online one month back. As you can see in the picture it is healthy when purchased. I am keeping it on my desk which is getting afternoon sunlight from a west-facing window.
You haven't mentioned your watering routine for this plant.
This condition probably happened due to watering issues, and my assumption is, you probably didn't water the plant for too long which is why the leaves have shrunken and became soggy and so the tip of the branches. Water it immediately, it can still be saved.
Jade plants are succulents. That means they store water in their leaves, which is why the leaves become fleshy. It can stand a few days without water depending on the climate, but after a while it will require water. If you do not water it on time, it will start consuming the water stored in its leaves and gradually no longer will be able to hold its structure.
Also over watering will cause a root rot and eventually the plant will die.
So, you have to be cautious when watering your succulents. If and only if the top two inches of the soil becomes dry, water it thoroughly and let the extra water drain out and wait for next turn.