How to Deal With an Irate Customer?

Sonia's computer crashed while she was finishing a special assignment for her work. As she is very stressed, she decided to go to the store where she bought it to see if they could help. A technician receives the computer and asks what happened to it$.$ She answers him nervously, and he tells her that she should leave the computer to get a diagnosis. He said that he would call her to let her know.

What are some things that the technician must do when dealing with a client that is under stress?

When making an on$-$site service call, what should you do before making any changes to software or before taking the case cover off a computer?