How to check your Samsung android phone before buying

If you are going to buy a used Samsung android phone from any seller, you have to check it’s quality first, you see if you sell your Samsung or any company’s phone to a shop then those trained workers will check the quality of your android device, but if you will ask them what is the code to check it , then they will never tell you this ,they always say this is a secret we can’t tell you but the fact is if they will tell you then you will also check the phones that they will sell you later, that’s the secret why they are not telling you ,so don’t worry friends I am here to tell you in detail –

First dial this number from your Samsung android phone- *#0*#.
Then a screen will be opened with a number of options there as shown in this picture-
First press touch option to check your phone’s touch screen, it will let you draw lines across the corners and a cross in the centre of the screen, many Sony phones will let you draw lines all over the screen to check it. So lets back to Samsung if all the lines have been drawn successfully then it means your phone has passed the touch screen test, a pop up will appear on the screen to show it with a message PASS on it.
Next is sensors, it will let you check all the sensors if you will put your hand in the front of the phone it should vibrate and should change the screen color to green, down there it will show the other sensor’s status as compass and many more.
Next is sub key, it will let you check all the keys of your phone that whether they all are working properly or not, on pressing every key the screen color will be changed immediately, it includes checking of the power key,home key,option key,back key and volume key also.
Front Camera option will let you check your front camera, this option will not appear on the phones without front camera.
MegaCam will let you check the main camera on your phone.
Vibration will let you check if the vibration is working properly or not.
Sleep will let you check the sleep the feature, pressing this option will result in immediately closing of your screen.
Dimming will let you check all the red, green,blue colors by dimming it.
Red,Green,Blue option will let you check RGB, on your phone, because on your phone all the colors have been made by the combination of these colors.
Reciever is related to checking radio frequency.