Is this phone a refurbished one?

It is not easy to find if a phone has been refurbished or not. For Samsung phones though, the app you mentioned - Phone Info *Samsung* is a great tool to get a lot of data about the phone. If the app is not giving a clear response that the phone is refurbished or not and is just giving an error that serial number does not match the manufacturing data then it can be a problem with the app too.
You can contact the app developer for more details otherwise if the phone can be replaced with another piece then you might opt for that too.

sndeep.info/en is not that a trustworthy website and I won't go by what it says. How about writing to Samsung directly to ask for a solution to this?

I have gone through one method in which you have to long press an empty space in your home screen and once you get the 'add to home screen' menu you have to select 'shortcuts' from it.

After this a shortcut menu will display in which you have to select 'Activities'.

Now you will be seeing various entries with different headings. Search for a heading containing 'hiddenmenu'. If you find it then within this heading, look for the entry RTN and select it. Inside the RTN you may see various items like total talk time used, whether it is refurbished or not etc.

If your phone has no homescreen launcher app then you may have to install launcher pro or ADW launcher or some similar app.

There is one method I used on my phone when I owned a Samsung device. I am not sure whether it does work now.

• Dial ##786#
• You will be taken the RTN screen.
• Check and tap on View option
• The screen will show you several RTN options.
• Scroll down to Reconditioned Status. You should get two options Yes and No.

If the code does not work on your phone, you may try *#*#786#*#*.

However, if the phone has undergone a repair or you have installed any custom ROM on your phone - the procedure may not work. The best option would be to get in touch with Smasung directly. Provide them the serial number and other details and request to let you know if the phone is refurbished or not.