Plus electrical short is one of the common faults GSM phones. Maintenance should first determine the short-circuit in a battery powered directly part ( such as power amplifier, power control , battery backup , power block , charging module , etc. ) or in the load circuit power supply input . Since GSM phone power ( especially through manifold power supply GSM mobile phone ) to work with logic circuits have a very close relationship , a lot of mobile phones in an instant power- supply circuitry would like to load , but pressed the power button , reset circuit yet start , so the phone is not running the boot process , so in this type of phone, if the power output load partial short circuit can cause electrical short-circuit fault applied with the same battery powered directly partial short circuit performance . Short circuit judge 's approach is to reduce the supply voltage , it is not enough work to promote the power IC (3V or less ) , this voltage is no longer applied if a short circuit occurs , then the point of failure in the power supply output load ( including logic IC internal or the pin is shorted to ground ) , can touch the law , local power supply method or step by step method to find the point of failure ; if still short circuit , then the fault in the power circuit or directly from the battery -powered circuits, such as amplifiers, power control , warning circuit, focus on examination of the circuit in the power supply filter capacitor, high voltage gradually available with the touch method to find the point of failure . The above-described method for mobile phones high fault , the same applies .dQxservice manual download site