Ca n't be sure about that , though . One step at a time ... " Andy watched , fascinated , and did n't interrupt again . Castin worked with his laptop battery and the elevator 's wiring , cursing a lot as he went .

Question: Why is Castin so frustrated that he is reduced to cursing ?
Answer: Castin is unable to stop getting mad at others .Castin is unable to fix the clock .Castin is unable to empathize with others .Castin is unable to understand the electronics .