Why you need to buy a used phone? May be its cheaper for you. Or you need a temporary phone to use. But you have to think before you buy it. Why the seller is selling the phone?
Most of the seller want to sell his/her phone because he want to upgrade his phone. To buy a new phone he/she sell old phone and add money to buy new one. But sometimes there are some people who sell device when it became faulty. You will face many problem after you buy it.
Things you must check before buy a used phone:
Is the display and touch working properly? Or the display is original one not replaced or repaired? Try to check the same phone from another person, so you can compare all the things. Sometimes the touch may not work in the full display area. So you will face problem while typing or using any app or playing a game.
Check the sound quality both hearing and mic. Connect a SIM and call in the phone you want to buy. Listen the voice you are hearing in this phone is enough or not. Same way talk in its mic and listen from the other phone, check its mic voice is clear or not.
Check the headphone port working properly or not. Check bluetooth and WiFi also. We saw many phone where WiFi was not enabling. Check the phone can use cell phone data in network mood. The phone may have 4G/LTE but it may cant access 4G/LTE network.
Check the battery health and charging. Sometimes the charging port may be faulty and it will delay charging the battery. Check the battery level and restart the phone few times. If the battery became very weak the battery will loose its power quickly during these restarts.
Sometimes the phone motherboard also become faulty which drain the battery quickly and heat the body without any reason or simple app use. So its very important to ensure that the phone motherboard is not draining the power. And no over heating.
Check the camera is working properly. Sometimes old phone camera image sensor doesn’t work properly. You may can’t get proper image tone from the camera. Sometimes it become blurry. If the glass in from of camera damaged or scratched the camera will unable to take clean photo. Check the noise of the photos. Any camera can be noisy after using certain age. Some times new phone camera can get noise if it is faulty. If the phone has multi camera, make sure all cameras are working.
Check the data cable is working. Some times the phone cannot connect with PC if there is any problem with connecting port.
Also check that the phone has a valid IMEI.