The checking will be like what 2nd handphone shop do.
(check for update and do a clean flash)
1.Check for any cosmetic damage.
2.Test wifi, mobile network connection can work well for a few day.
3.No unnatural battery drain detected after a few day use.
3. Touch screen test to ensure it response well and no ghost touch.
Test full brightness and min brightness for tint or burnt issue.
4.Do voice recording and play back and make sure mike works well.
5. connect and sync BT devices. BT headset to run music and video see that the music do not cut off within 5m (unblock)
6.Stream you tube 4K and play for a few min. Skip and see the buffering kicks in fast.
7.Test each cam. with pic and video. During video put hand in and out to ensure pic can auto focus.. Main cam have hardware anti shake so walk and take some video. it should not be super shaky.
8.copy some big video file to the phone 1+gb will do. see tranfer speed is ok.
9. Test both speaker got sound and at high volume no cracking sound. Unless the music u play is bom bom type.
10. make phone call with a friend and make sure it is clear and his reply is clear.
Most of the items is just to see if you are ok with. like cosmetic if some insertion mark at the USB C port is found unless it is really bad. I likely will just ignore.
I also notice the pic review in Win is also ... I do not think many buyer will cut crop and deco the picture to post.
Gam xia bro. Will follow your guide. Hahahaha.

