Android Secret Codes 
Generic
These codes are mostly universal, and should work on Android devices, no matter the manufacturer. There might still be carrier restrictions on certain codes though, so they're not all guaranteed to work.

*#*#4636#*#*
This code can be used to get some interesting information about your phone and battery. It shows following 5 menus on screen:

• Phone information
• Battery information
• Battery history
• Usage statistics
• Wifi information

*#*#7594#*#* 
This code can be used to change the "End Call / Power" button action in your phone. Be default, if you long press the button, it shows a screen asking you to select any option from Silent mode, Airplane mode and Power off. You can change this action using this code. You can enable direct power off on this button so you don't need to waste your time in selecting the option

Many of the above codes will also work on Samsung devices, but the below codes were tested specifically on Samsung devices, and we can confirm that they should work on them (subject to carrier restrictions).
*#*#232338#*#* - Shows WiFi MAC address
*#*#1472365#*#* - GPS test
*#*#1575#*#* - Another GPS test
*#*#232331#*#* - Bluetooth test
*#*#232337#*# - Shows Bluetooth device address
*#*#34971539#*#* - Show all camera information
*#*#197328640#*#* - Enable test mode for services
*#*#232339#*#* - Wireless LAN test
*#*#1575#*#* - Test your GPS (alternative to generic Android GPS test)
*#*#0*#*#* - Test your LCD display
*#*#4986*2650468#*#* - Display crucial phone information (PDA, Hardware, firmware etc.)
##778 (followed by the Call button) - EPST menu

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