Also, it was transplanted to a larger container from a smaller one, but the roots were still contained (in the shape of the smaller pot it was in) so I'm also wondering if maybe some of the roots haven't gotten any water and some have gotten too much.

You have a lot of right ideas I think. Yes, it looks like it was overwatered. It looks to me that the smaller pot would be more ideal, as the roots won't grow that fast, and succulents don't mind being a bit root bound.

I would get some perlite from any garden center/Home Depot/Walmart. Mix this with the soil you are already using in a 60% perlite and 40% soil proportion. It will look like a LOT of perlite, but that is what it is supposed to look like. When you repot, completely bare root the plant. Don't be afraid to use water to get off the soil. Look for mushy roots, and cut off any you find.

The plant should perk up after a couple days, and if it doesn't, you probably have a rot problem. If that should happen, just report back here, and we will help ;)

~palmsandsnow

Thanks! I don't have any perlite, so I'll probably try to go get some this week. I went ahead and bare rooted the plant (as much as I could get, the roots were pretty dense by the base. I got probably 80-90% of the dirt) and I just have it sitting on newspaper to dry at the moment. I figured the sooner the roots can dry out, the better. I know I lost some of the roots while I was doing it cause it was super packed, so hopefully that won't hurt the plant too much :/ On the plus side, I didn't see any mushy roots while I was doing it and the base looks solid, so it doesn't seem like it has rot.

I dont think its rot; if it was the base would be the first to die. To me it looks overheated. Where are you located? If you are in the southern hemisphere, this would make sense, since it should be close to the peak of summer there. Mature plants are able to take heat waves better.

It's inside our house in Missouri, and it's definitely winter here. We usually keep our house between 66 and 70 in the winter. And I have it in a south facing window.

Ignore all of that then, lol. I dont think its a water problem though.

Is it over a old style radiator or electric baseboard where it could get overheated?

It looks thirsty, the pictured soil looks like it has a lot of peat in it, which when it dries will resist absorbing water. You may have thought it was getting enough water but the water could have just been flowing around the root ball and out the drainage hole. You could give it a good soak with its roots bare until you can get your perlite, just stick it in a cup of water for a few minutes and make sure it is able to dry properly when done. Also, I don't have any personal experience with this plant but others will say that variegated jades are pretty finicky.

Crispy-dry leaves and limp stems usually happen when plant is thirsty. 66 - 70°F is warm, so some water is needed.

If the soil plant was originally potted in contains lots of peat, it could have become hydrophobic and regardless how much you water, roots are not getting any moisture. Water is repelled and just drains out, or soaks only into new soil you added around the original. You said you are having hard time to get it off the roots. Try bowl with warm water, swishing the root ball in it. Dry peat will re-hydrate a bit, and you will be able to get more of it off.

Over-watered plant will also have limp stems, and leaves often get yellowish color - too much water in them. This yellow is quite faint on variegated jade, but leaves would be also softer & plumper. Stems could start getting darker if rot started (I do not see that in your photos).
Once potted into fast draining mix, use bamboo skewer/chopstick test to know when to water. They get best color in lots of light.

Thanks for all the input, I'll try out getting as much of the dirt as I can away from the roots and repotting with a new soil mix. It isn't above a heater, and we don't have radiators so it shouldn't be getting more heat than just the temperature of the house.

I got it repotted into a pot that should drain better, and I added the perlite into the soil. How often should I be watering it to catch it up if it is under watered?

Still too much pot / soil for that plant - it should have about an inch of annular space for soil around a rootball of that suspected size.

Agree with Jeff, pot is too large. Have a look at photos I posted - you can see size of the containers. The big plant (17.5" tall from the soil line) is in pot smaller, or maybe same size as yours. And they are in very gravely mix (grit+perlite+turface, nothing else) that drains very well. That much soil will take forever to dry up.

Plant should be watered when the potting mix is dry. You can find out by using bamboo skewer or chopstick; stick it deep in the mix, avoiding the roots. When taken out and is dry and clean, time to water. If there are tiny particles sticking to it and it feels cold/damp when touched to top of your hand (or your cheek), there is still plenty of moisture and do not water.