Final answer:
The first action to take when a monitor is not working is to check power and cable connections, as this is a common cause of display issues and can be quickly resolved.
Step-by-step explanation:
If you've received a trouble ticket that the monitor is not working, the first thing you should do is B) Check power and cable connections. This step ensures that the monitor is properly connected to both the power source and the computer. Simple issues such as loose or disconnected cables are common and can often be the cause of the problem. Before considering more complex solutions like reinstalling display drivers, replacing the graphics card, or updating the operating system, always start with the basics. By verifying the connections, you can often quickly solve the issue or rule out a potential cause.