1. Check if the system can recognize the “Security OS version”.
Settings->about phone-> Security OS version;
2. Check if the welding of the CON2 small board and its peripheral components is normal;
3. Check if the NFC_5V voltage is normal;
4. Check if the 27.12m (Y3) crystal oscillator starts vibration;
5. Replacing the NFC antenna;
6. Replace U1