When iPhone 6 Plus hard disk come across some problems, what should you do? Maybe you should try these steps. If you need some phone repair guides and tools, you can follow vipfixphone. Good luck for you.
1. When I receive the motherboard, it has no NAND Flash and many jumping wires on PCB with Flux Oil Paste, as shown in picture 1-1.
2. After observing the outer looks of the motherboard, I 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 1-2), 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. I guess that someone must jump the wrong wire.
3. As shown in picture 1-3, when scratch the Flux Oil Paste carefully, I 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 I can be sure that the customer has jumped the wrong wire.
4. Re-jump the wire and paint Flux Oil Paste. 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 and find other two joints that are jumped the wrong wire. Fix them one by one. Although that costs me a quarter, it is useful.
5. After assembling 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, after discussing with customer, I use the other workable motherboard to replace the original one. Trouble is removed.