How to test mobile function?

Samsung’s Galaxy smartphones have a built-in diagnostics tool that's accessible from the keypad. Open the Phone app, tap the Keypad, and then type *#0*#. A diagnostic screen pops up with buttons for a variety of tests.

Tap Red, Green, or Blue to test those pixel colors. Tap Receiver to check the audio, Vibration to try the vibrating feature, and Sensor to test the accelerometer and other sensors. You can also tap Touch and then move your finger around the screen to test the touch screen and tap Low Frequency to test low-frequency sounds.

After your test is done, touch the screen or tap the back button to return to the main screen. Tap the back button from the main menu to return to the Phone app.