Most of smartphone owners mostly probably already heard about service codes (“diagnostic”, “magic” etc.) for their phones. Such codes are entered in the dial screen and allow access to restricted parts of the phone. Some of them modify phone’s internal settings and sometimes may even damage the phone if not properly used.
There’s one special code though, which works on most Samsung devices with stock firmware, is safe to use and provide some useful diagnostic information about the phone.
Open the dial screen and type: *#0*# . Backlight of the phone will be boosted to maximum and a new menu will appear, allowing testing most of phone’s features.
Among these you will find filling the display with single color (red, green, blue, black), testing the vibration engine, display dimming, checking both cameras, checking status of all sensors, testing touchscreen (also screen hover and S-pen if device supports these features), speakers, phone keys, notification LED, IR LED and more.
Note, that exiting from most diagnostic screens require double back-key press.