here is the useful tip
1. kunin ang imei, napakaimportante nyan
and check to iunlocker.net, para maverify ang info if same ba sa phone
2. check battery health, syempre mas maganda kung 100%, check mic, earpiece, wifi, volume button, toggle swith, speaker, fingerprint sensor (pinakaimportante po ito, kasi 1fingerprint id lang = 1 apple cpu id )
3. eto, kung my shorted sa board, itest mo ung phone sa videorecording with flash ng mga 30 minutes, dapat nd agad babagsak ang battery percentage. tas take a photo with flash on mga 40 shots.