Going to buy a 2nd hand phone weather android or ios or java and Symbian based but java and Symbian are outdated now. so we only consider about android or ios devices.
So main points to remember-
1.The phone u r going to buy check weather it is under warranty or not take the bill from seller.( easy for repair)
2.If warranty not matters to u check the company web site.search is company making parts of this phone yet or not. ( Don’t buy such electrical device because it may fails any time and u can’t able to repair that) .
3.Now download device performance app on the android or ios device.
- Run the app and it will tell u is camera , ram, sensors, screen , battery is working properly or not.
5.If all ok its time to buy the phone at lowest possible price u want.