7 Reasons for iPhone Booting Failure

If you are a cell phone repair technician, I think it 's really common for you to fix this kind of fault: iPhone booting failure. Why iPhone is suddenly unable to turn on? How to fix it with right method? What repair tools you need? In this article, you will find all the answers:

1. large current value

Use DC power supply to have a test, If iPhone 5S has large power current and fails to boot, it is often caused by one of the circuit from PP_BATT_VCC or PP_VCC_MAIN is short-circuit, the solution is same as the power leakage repair.

2.No power leakage when power off, large current when press power button

This situation is a short-circuit of the output of the power IC. Measure the ground resistance of each output of the power IC with Fluke 15B+ Digital Multimeter , and find out where the short-circuit part is. Then replace it.

3. Booting with 50 Ma Current

Most of this fault is caused by the iPhone 5S CPU or NAND is damaged, repair will be very difficult! Because the iPhone NAND is not a single change, and the cost of CPU is also expensive, the success possibility is not big, you will only only waste money but also time, so it's best to give up in this situation.

4. Booting with white apple screen, reboot after blue screen , many lines of English, red screen or reboot after constantly changing the iPhone 5s screen color.

If you turn on with the white apple screen, you need to find out that it doesn't boot or the display is abnormal. You can connect Ace assistant after boot. If you can boot normally, you can connect online, and Ace assistant can read the information of the cell phone, which means that the phone can boot normally. If Ace assistant prompts "point trust", it also means that it can boot normally. So the problem is shown in the display part, the solution is to restall or replace the iPhone 5s touch IC.

5.U2 damage will cause the boot failure, white apple screen, boot current value stays at 200MA, In most of case, U2 chip damage will cause white apple screen or current value stays at 200MA.

6. The iPhone 5s stays in recovery mode when customer sends to repair. Recover the device to see if there are any error code, if it reports error 4013, then you need to replace a compass IC or U2, if not working, replace a new NAND. if it reports error 9 or 14, it means U6 or NAND is damaged, firstly replace U6 chip then try to replace NAND.

7. if the boot current value is around 50 Ma, connecting computer will automatically enter the DFU mode, which is mostly CPU does not work, in this kind of case, you can check whether the resistance surrounding the CPU is false welded or dropped.

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