Please follow below steps for troubleshooting：
1. Update firmware to latest version：In【Settings】→【About】→【System update】, Tap 【 Check Update】
2. Access to Safe Mode ( long press power key → Tap and hold【Power Off】→ Tap【 Ok】) ： If your phone / tablet works well in safe mode , malfunction might be caused by 3rd party apps. Please reboot your phone / tablet and check again if it works well.
3. Backup your data and perform factory date reset.
