A Failure to Communicate

How does Chava transmit to the Nachash the command not to eat from the Etz Hada'at vs. how the command was originally given?

God commands that Kayin does Teshuva, why does Kayin react the way he did?

Was there a deliberate misunderstanding in each case?

Delivered at the OU Israel Center, September 12th, 2018/3 Tishrei 5779