Open phone, power on boot, refer to figure 3 to use oscillograph check V502 c, 13MHz clock waveform, and normal. Then cymometer its value is 12.9960MHz, the offset has occurred. Key suspect G502 and AFC control voltage. G502 1 foot AFC voltage with multimeter is only 0.1V, the normal value should be 1.1V. According to the circuit diagram, AFC voltage from N100 audio module, welded N100 failed, after removing N100 replanting Tin back, checking AFC voltage has returned to normal, power on the net, and the glow sticks, and troubleshooting.Wu2service manual download site