The phone has no issues. The back shell has been changed. I did not buy this phone originally; I exchanged it with someone. I always use Wi-Fi, so I did not check the mobile data. When mobile data is turned on, it sometimes shows E and sometimes 4G. After showing it to a technician, they said it would be fixed with the next update. Other than that, there are no issues with calls or SIM network connectivity. The display and fingerprint sensor are 100% functional.