posible problems: 1-pin charging pin or charger defective (false contact, instability) 2-defective battery (if it does not exceed 5% but the phone dials that it is charging, it is the battery) 3-integrated charging circuit defective (in case the phone does not charge at all) 4-defective charger head (it may not be sending enough current) 5-capacitor failure, resistors or diodes. possible solutions: 1-verify which one is failing, try with at least one more charger that is in good condition, in case the charging pin is the one that is failing you will have to replace it, in the same way if it is the usb cable 2-change battery 3-load IC replacement 4-head change 5-testing, identification and replacement of short elements.