SOLVED: iTunes shows 4005 error code after NAND expand on iPhone 6 Plus

Here is a advice, when you expand the NAND memory Flash, you'd better more carefully or find the professional to do it, because it is very easy to damaged your iPhone. Here is a case, when someone expand the NAND of iPhone 6 Plus, 3/4 solder joints have been dropped, then jump wire to it, but when root it, it shows 4005 error and screen shows white Apple logo. Let's see what's going on.

When we receive the motherboard, it has no NAND Flash and many jumping wires on PCB with green oil, as shown in picture 6-86.

After observing the outer looks of the motherboard, we use multimeter to measure the diode data of all the solder joints and they all have data. But, comparing these data with that I get from my previous repair cases (picture 6-87), I find that pin G5 should be about 700 and J5 should be about 500 (notice: different multimeter shows different data). While these two joints is about 700. The two data should not be the same. We guess that someone must jump the wrong wire.

As shown in picture 6-88, when scratch the green oil carefully, we find that there is a wire and a via. Measure its diode data. The data of wire is about 700 while the data of via is about 500. Now we can be sure that it is jumped the wrong wire.

Re-jump the wire and paint green oil. Use multimeter to Measure the diode data of pin J5. It is about 500. In case of other problems, measure the diode data of all the solder joints again under the stereo microscope and find other two joints that are jumped the wrong wire. Fix them one by one.

Then assemble the NAND Flash, root it again. The screen still displays white Apple loge without the progress bar. But iPhone now can recognize NAND Flash because it shows white Apple loge in seconds. I presume that CPU is pseudo soldering or the board is disconnected. Considering the stability of whole iPhone, we use the other workable motherboard to replace the original one.

Finally, we test it and all is fine, the 4005 error code was been solved, the iPhone 6 Plus can back to normal work.