Solved: iPhone 7 Plus unable to enter IOS and report error 9

 Here is an iPhone 7 Plus accidentally dropped into water, it still can be used normally when we clean up the water, however, it can't be used after a day. The problem is that after press the iPhone power button, it always auto restarts. When we re-flash it with iTunes, it reports unknown error 9. We have to solve it. 

According to our experience,  the iPhone Nand flash and iPhone logic epprom IC all can cause this problem. Now, we need to disassemble the iPhone 7 Plus first.

Use phone opening tools to disassemble the iPhone 7P, take out the iPhone motherboard. Use digital multimeter to measure the power supplu of the iPhone Nand flash, the  3V, 1.8V and 0.9V all are noraml.  

Check iPhone motherboard under the Stereo Zoom Microscope, we know that the iPhone Nand flash and iPhone logic epprom IC didn't been repaired, but the iPhone baseband part did. Leave it alone, now we try to fix it by replacing iPhone Nand flash, after replacement, it still reports unknown error 9, then it may problem of the iPhone logic epprom IC. Directly replace the iPhone logic epprom IC, after replacement, it still reports unknown error 9.

As we know, when the resistance value of the two resistors that connected to the logic epprom IC is too large, it will also reports error 9, try to replace these 2 resistors. Remove the iPhone logic epprom IC and the resistors that connected to it, and then with the help of the QUICK 861DW hot air rework station and Titanium Alloy Tweezers, we replace all of them.

After replacement, re-flash the iPhone, now the process bar is running normally, which means the iPhone baseband part is no problem, the iPhone is basically repaired. 

After the flash done, press the iPhone power button, now the iPhone 7 Plus can be turned on smoothly, and it is entering the IOS system successfully, all functions on iPhone 7 Plus tested are normal.