The user uses the phone while charging. The cable acts as a lever. Repeated rocking back and forth stresses the solder joints. A microscopic crack forms.
You have to wiggle the cable to get the lightning bolt symbol. The phone charges only if the cable is bent at a precise 23-degree angle. This is the user's "red alert," though many ignore it. Phone Micro Db Crack
The cable clicks in firmly. Charging is reliable. The user uses the phone while charging