iPhone 5s - Blue Screen issue, possibly related to NAND CRC error in panic logs?


New member
Hey everyone,

I see this board getting mostly used for questions about Macbook Board Repairs, but I was hoping anyone has some more experience then I have at iPhone (board) repairs.

I got this iPhone from a customer and I'm starting to suspect an issue with the NAND.

At first it wouldn't want to install, I was able to resolve this by removing the camera module from the board, I've tried it some additional times and restoring with the camera would always give the same results where restoring without the camera would make it pass the first step (Copying the actual firmware to the phone).
After this the phone would reboot and crash between 1 and 8 times with the blue screen issue before the iOS Welcome screen would be displayed. (2 crashes left logs behind, you can find one of the kernel panic logs in the bottom of this post). After configuring the phone and being shown the home screen the phone would crash while in standby every 2 to 6 hours, it crashes more often if its being used. (Either because it generates heat or because of more I/O being used?).

The youtube video was taken after an attempt to install an application from the app store, the only way I was able to boot the phone back up is by shutting the phone down and waiting 10 minutes before booting it up again and is now booted and working again. (Video down below)

Question: Is this a NAND issue? Would it be worth trying to reflow the NAND chip?
Getting a replacement NAND is quite expensive because of the 64-bit NAND programmer I'd have to buy. If that's needed I'd have to look into it for a bit to see if it could be a worthy investment.

Confirmed working after installation:
- Compas
- Earpiece and main speaker
- Microphone
- Front and Back Camera
- WiFI/3G/4G/Bluetooth
- Digitizer&LCD
- USB (Syncing) and Charging

Parts I've tried to replace (Currently back to running its original parts):

- Lightning/Headphone "USB" board
- Back Camera
- Battery
- Display (Although not while also having the other replacement parts in use, I just tried a different display)

I've also tried running without Touch ID and The Power button / Volume buttons connected without success

Kernel panic: http://pastebin.com/J6ypzhP0
Video of the device crashing: https://www.youtube.com/watch?v=Zg2zA2M5Ku8

Thanks in regards!

(Also yes, I know the time spent in this repair is not worth it economically. However I actually like to repair devices and its been a bit quiet recently due most people being away for holidays. Might as well spend my spare time trying to repair and learn things, right?)
Last edited:


New member
check screw damage at the bracket from lcd connector
I was quite sure it wasn't screw damage.

I proceeded with reflowing the NAND and that seemed to resolved the issue. Restored the device 3 times with no issues over a period of 3 days (I also kept it running in the mainwhile to check for any reboots or crashes). I'm not sure if reflowing the NAND actually is what fixed it or that I was just lucky that another component got heated close to it, but it works and the customer is happy. (I made sure to let him know of the 3 month warranty though, I won't be too surprised if this one comes back with the same issue but I hope for both me and the customer that this actually resolved the issue)


The NAND has underfill under it, a real reflow would kill the phone. You just did the "oven" trick and I qualify this as a garbage repair and it will fail again. Stop doing this crap!


Active member
Totaly agree whit dukefawks on this.
This is no Repair.
Did you remove underfill and removed the nand?
Rebaled and replaced?

Did you check board for Signs of damage microscope exam etc


New member
Heated the surrounding area up to about 200C with my hot air station, its indeed not a full proper reflow which would've been made difficult because of the underfill. Also replacing the NAND would've been hard due the need for a NAND reprogrammer.

I warned the customer before accepting the work (After the first initial diagnose) that I can't promise it will last but he was more then happy just so that he could wait for a couple of months before the release of the iP7. The price of a full NAND reflow/reballing would've been high in comparison for a second handed iPhone 5s, which is going for about €200. Also from the small conversation I had with the customer didn't make him sound like he actually wanted to spend a bunch of money. (Kinda like the "Can't you apply magic and get it fixed for cheap")

I fully agree that a full replacement or reballing of the NAND is the proper repair and its exactly what I'd do if a customer is up for paying the full price, but when I can offer a customer a major discount by applying a temporary fix just so it will get through two months its alright in my opinion too.
At no point the customer wasn't aware of the risks and quality of the repair.

Did you check board for Signs of damage microscope exam etc
I did a small check and all commonly damaged area's looked good. Its also to note that the iPhone did not have any prior repair attempts as far as I'm aware of. (All original parts, no scratches, no finger marks and the screws didn't look used)


New member
I had a same issue with iPhone 5S and many said that it was the NAND issue but found out that is was the U16 Chip. Had with iPhone 5 and 5S and by reflowing it usually fixes the problem. Sometimes i even change them to newer ones and phone works great.

You maybe reflowed the U16 because its under and near the NAND chip.


Active member
i am confused isnt the u16 the compass ic ?
that chip when its broken gives kernel panic almost same as bad proximety /camera kabel.
also i dont see that the u16 is close to the nand on a 5s board heating is kinda off direction imo (it gets heat indeed, but inuf for reflow......) HTB1UBXQHpXXXXaiaXXXq6xXFXXXn.jpg


New member
I was confused also but seems to work when replacing U16. I don't know why it gives kernel panics but it did. I habe used the phone now over a year and works fine when i replaced the chip.


New member
1.BS1,2 (base screw)
2.Compass IC
3.Tristar U2 USB IC
4.U6 Eeprom
5.LCD voltage supply IC


New member
Yes,in this order.
For me most common is USB IC or BS 1,2
Red screen: prox/front cam ribbon


New member
Depend what you are asking for.
I don't know a lot about Macbooks but I do phone repairs as a hobby so I'll try help if I can.
About blue screen I found also few other components on ZXW


they are not in any order,but like I said BS lines and U2 sometimes PMU were cuplrits in my cases.



New member
Well lets say an iPhone is water damaged. What usually gets fucked up and when its not good to fix a phone? I know a lot about MacBooks but starting to fix iPhones so it would be nice to know something about them.

Anything you know would help me in future. Thanks!


New member
For me,it's always worth as I'm doing it as a hobby.
I don't clean a board at the beginning but after an inspection.
First visually inspection,try poke corroded components and check if they come off.
Then remember most bad looking places - may be useful hint for later.
Check battery connector readings and VCC_MAIN(main lines) (diode mode in both directions,one direction it's not enough)
Good readings (depend of phone) should be approx 350/OL for battery and 120/OL VCC_MAIN
Try power on MB,(I'm using DCPS and "Power Cables PRO 2" instead battery)


Check power consumption on DCPS or connect USB cable and you will check USB IC in the same time.
Check if something getting heat (I'm using Flir one for android and it's a great tool or use lips or IPA)
If yes,mostly you find a culprit or some component on IC line is short as you know.
If not boot then probably USB IC or PMU (replace)
If any other issue appear later then corrosion under some not underfilled IC or small component is burned or pads are corroded or some mystery.
Connectors are a good source of information. Check readings in both ways (diode) or resistance (for me is slow) and compare with good board.
Write it down and you will be have it for later (probably you exactly know that already)
Also pads readings under IC's are good source too,but sometimes even when they are good I can't find a problem (still need to work it out)

I don't know what else at the moment,do your own procedures and follow them.
For me Macbooks are a mysteries but maybe one day I'll join to discussion.


New member
Thanks! That was alot of infromation and also that aliexpress link to the adapter to battery. If something else comes in mind i will ask. :)