So my bucket of Satin Ice had about 5 lbs left in it, and apparently i didnt snap closed the top all the way. I went to use it and it is all crusty, cracky and hard... can this be saved???

You can try to cut off the dry pieces which should be on the outside only depending on how long it was not closed. Then just knead what is left.

Another thing to try is applying some heat. Normally, i stay away from nuking my fondant, but if it's a lost cause anyway, it can't hurt. Sometimes the heat from the microwave, (at about 10 sec intervals) can help make it so you can need in some of the drier parts.