Trouble shooting is the process by which we can solve problems starting from the begining of the chain of situations that could go wrong, in this case if the monitor is not displaying anything we can check if the monitor cable is actually connected to the CPU, so pluggin the power cable to the computer would be a good first step in troubleshooting.
The term usability refers to the usage value of products, how much they can be used and their value after their use. So adding on these points usability helps to quantify the financial value of IT components.
