Power button
Press to turn on the computer if it is turned off, in sleep state, or in hibernate state.
Display Built-in Self Test button/Input-source selection button
This button has two functions:
When the computer is on, use this button to select the video input-source.
Press the button to switch the display between the internal system display and HDMI input.
When the computer is off (there is no power; neither is it in sleep state nor hibernate state), use this button to run the built-in self-test for the display.
Press and hold down this button, and then press the power button to turn on the computer. The built-in color pattern for the LCD monitor will appear on the screen.
For more information, see the Troubleshooting section in the Service Manual at Manuals at Dell Support Site.
Service Tag label
The Service Tag is a unique alphanumeric identifier that enables Dell service technicians to identify the hardware components in your computer and access warranty information.