Did you change anything since the last deaths? Keep in mind also that since they were not getting the ocean salt water, that the nutrients they needed from that same water were not obtained, and the crabs could be suffering from malnutrition, and may not be saveable.
Wasn't there something about your substrate as well, you were using forest bedding? Did you change that?
Let us know, lets see if we can help you save the crabs you have left.
