1. The mobile phone battery without using and no charging for a long time, resulting in the battery voltage below 3.4V.
Solution： Recharging activation.
(It is recommended the charging current shall be 5V/1A for about 30 minutes, and the unused battery should be charged every 3 months）
2. Mobile phone battery protection board IC cold solder joint, resulting in battery voltage output abnormal.
Solution: Return battery for maintenance.
3. FPC cold solder joint, fractured.
Solution: Return battery for maintenance.
4. Connector cold solder joint or damaged.
Solution: Return battery for maintenance.
5. The mobile phone battery connector is not in contact well with the phone.
Solution: Reinstall the battery and make sure the battery is in good contact with the phone.
