Are going to buy a second hand phone? than read this full and also rate it.
So what you need to do is: -
1) Check out the screen that it had broken or not, because some phones original screen is costly.
2) Check out the battery if it is removable or if you can see that it is not smelling something odd than a normal battery or it is good or not.
3) Check out the sound system by playing videos or songs that the speaker is not creating a odd sound.
4) Check the cost of that mobile on different websites if you’re buying the mobile online.
5) Check every thing about that phone and buy that if you’re sure that everything is all right in this phone.
I hope you have understand something and if you will buy a second hand device than you will remember the above points.