Most modern Android devices come with a hidden diagnostic menu that allows users and service center folks to test various components of the phone easily.
Usually, this diagnostic menu is accessed by entering some a particular key combination. Samsung had included a diagnostic menu on the Galaxy S5, and the Galaxy S6 and Galaxy S6 edge are no different. The hidden menu is also a great tool to check that the phone you are buying from the store has no issues with the accelerometer, dead pixels on the AMOLED display, or any issues with the flash.
To access the hidden diagnostic menu on your Galaxy S6 or Galaxy S6 edge, simply open the stock Dialer app and key in *#0*#. As soon as you key in this code, the diagnostic menu will automatically appear on your Galaxy S6. (https://bobbergdesigns.com/) You can tap on the different options in the menu to test different components of your handset, including the accelerometer, rear camera, speaker and more.
So, the next time you think your Galaxy S6 or Galaxy S6 edge has a faulty camera or any other hardware related issue, make sure to use the diagnostic menu to test the part properly.