Usually the boot failure may be caused by some components, but we can't judge from its surface. The repaired phone happens boot failure and the attached file shows there exist leakage, so we doubt there exist one of charge components occurred fault, we have to disassemble it.
(Notes: the PP_BATT_VCC is the most sources fault)
Different fault will match different phenomenon, as a professional repair man, we should know enough more fault to increase our phone repair skill. We will analysis the possibility fault one by one.
-If there is no power leakage when supplying power, but it will get leakage or large current once pressing the power button, this means the short circuit parts exist on one of the output voltage of power IC, measuring each output grounding resistance of power IC, find the short one, and check the related components, rosin method will help you to fast find it.
Respectively measure each output of the bypass capacitance measurement resistance, find the short circuit parts. Use rosin to locate the specific parts!
In addition to the short circuit part would cause booting failure, the USB control IC damage will cause the failure of white apple screen. The damage of the compass IC will cause error 4013 after restoring white apple screen iPhone.
-If iPhone gets blue screen rebooting or red screen rebooting, it is means the abnormal work of NAND parts, you can try to weld U0301, if still not work then restall or replace the iPhone 6 NAND chip.
-If the boot is not responding, check whether the main power of U1401 output is normal. If abnormal, replace U1401, if there is main power output, replace the power U1201.
-If the iPhone 6 set at around 100 Ma does not boot, connect with computer online, if it cannot recognize the hardware, it means the iPhone 6 CPU does not work, try to reinstall or replace the U1202, if you can recognize the hardware, restore to see what error, if it's 4005/4014/9/14/40, basically CPU or NAND problems, reinstall or replace the NAND. The compass IC damage will reports error 4013, replace the compass IC will solve the problem.
-If the iPhone 6 doesn't turn on because of water damage, clean and weld the small inductance and resistance around CPU and power IC, many small resistors or inductors can be corroded and damaged, they are hard to see by eys, you can use a VGA 7-45X Trinocular Stereo Microscope microscope to check and solder.
-If it's a white apple keeps on the screen, the Ace assistant will see if it can read the information of the phone. If we can read the information, it will show that it can boot. The problem is in the display and touch part. The touch IC--U2402 U2401 can be reinstalled or replaced.
Of course, there still exist some other fault which can cause this failure, but it is okay, we should remember a normal iPhone should have a normal value, you can check it in WUXINJi. Hope what we share can rich your phone repair skill.
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