iPhone 6s Repair Unknown Error 4014 Tutorial

The iPhone 6s reported unknown error 4014 when flashing it. The current is measured as 57mA, DFU mode, flashing it and it reports 4014, which is consistent with customer description.

Disassemble it to check the iPhone motherboard, the iPhone Nand flash on this motherboard has been repaired, and when check it under the microscope, we can see that the iPhone NAND flash damaged.

Remove the iPhone Nand flash and measure its diode data, it is normal. Put Nand flash into the WL PCIE Nand test programmer to test it, unsurprisingly, the NAND flash is damaged.

Replace the new iPhone Nand flash and flash it again, the fault still exists. As we know, the iPhone 6S and later iPhone reports iTunes error 4014 mostly caused by nand flash and baseband issues. However, after measuring, we know that the iPhone Nand flash is good, so now the problem is iPhone baseband. Measure the diode data of baseband power LDO part and S1-S5 power supply, all is normal.

Flash it again, test the S2 and S4 when the White Apple logo appears, there is no power in either of these places. Since S2 and S4 have no power, it is possible that the baseband power supply does not work and then can't output power. Remove the baseband power, and then use Fluke 15B+ Digital Multimeter to measure it, we found the 55 pin is to ground.

55 Pin connected to the 19.2M clock, put iPhone motherboard under the VGA Camera 7-45X Trinocular Stereo Microscope to observe the 19.2M clock.

19.2M clock with C3501_RF capacitor grounding end connected together

Handle the baseband clock well, and then flash it again, now the progress bar can run normally, and iTunes doesn't report unknown error 4014 anymore. Read other cell phone repair tutorials on www.vipfixphone.com