How to do, If checkbox is checked it will uncheck the other checkbox?

I have three columns:

1. Task (text)
2. Assigned (checkbox 1)
3. Done (checkbox 2)

I want to create a ticket task sheet. If task is in progress, check checkbox 1 and task cell will turn yellow. I'm able to make this work.

But what I can't get it to work is: If task is completed, check checkbox 2, and will automatically unchecked checkbox 1, also, will change task color to green instead of yellow. I tried to use IF, SUBSTITUTE, or REPLACE but don't know how to get it to work.

Share and Edit link: https://docs.google.com/spreadsheets/d/1IT-GoMUwbNgVcr1kJMtR-1GcWVQREjiRav7kweoeZcA/edit?usp=sharing

Best regards