iPhone 6s stuck DFU black screen after change nand - GSM-Forum

art83 · 03-21-2017, 14:03

I have iphone 6s in which I changed the nand (from 16gb to 64gb). with the programmer I have reprogrammed the new nand with the old data. once remounted the new nand, the iPhone is left with a black screen. connected to the power absorbs 0.5a, and connected to pc, itunes detects it in recovery mode (dfu). when it tries to restart the phone to start the restore, the iPhone will restart in recovery mode again (dfu). so itunes waits of the iPhone (even for many hours, and than doing nothing).
the iPhone is always in dfu with black screen.

- before changing the nand, it worked well

I tried to reballing the nand, replace whith the old, but it is useless. always it stuck in dfu.
I haven't lost any component.
if I try to reset with power + home, it restarts dfu mode.
I tried to remove the C1515 (i read another post where a user say remove or replace it to exit from dfu mode), but nothing .... always in dfu
Now also with the old nand it remains in dfu

how do I fix?
the new and the old nand are properly read by the programmer, then work.

sometimes in the various tests of resoldering (while trying to reprogram the new nand, replace the old, increase the thickness of the bulle .....) instead of absorbing 0.5a, it absorbed 0.05A - 0.03A .... .

What may have happened? some short? some other component to remove, and then reballing and resolder?

please help! thank's

art83 · 03-23-2017, 04:31

I post with more information....

If i connect it to a psu, it indicate the iphone absorb 0.48a (ok in dfu mode, but it stuck on this mode).
One time, between the many test (when i remove, reballing and resoldering nand), the iPhone absorbed 0.03a immediately after 0.48a then 0.02a and again immediately after 0.5a.... all very quickly ... even one second between 0a and 0.5a

I think the nand is welded well .... but I can not find the problem ... there are no shorts (otherwise it would absorb more) and still using a product were not shown.

It's possible i need to reball baseband, or cpu (but is impossible i think... otherwise there is short, it is true?)??
Otherwise i try to change u2 ic????

Please help.....!!

clashsndsstm · 03-25-2017, 03:29

hello,
have same problem,
can you try restore with 3utools? which error you get? invalid serial nimber or smthng else?

TBC01 · 03-25-2017, 22:01

3utools will not restore neither will itunes, if the device is starting in HDFU and crashing it is because it cannot enter recovery mode when instructed.

Even without a nand it should get to recovery mode at switch over, this on ipads requires battery voltage don't think power management will run so no RM.

inspect at 40x mag I expect a disturbance of component or thermal shock under a local i.c.

nombatca · 03-27-2017, 01:17

Reball the CPU! Noway other man.

03-21-2017, 14:03	#1 (permalink)
art83 Junior Member Join Date: Feb 2017 Posts: 9 Member: 2686964 Status: Offline Thanks Meter: 4	iPhone 6s stuck DFU black screen after change nand I have iphone 6s in which I changed the nand (from 16gb to 64gb). with the programmer I have reprogrammed the new nand with the old data. once remounted the new nand, the iPhone is left with a black screen. connected to the power absorbs 0.5a, and connected to pc, itunes detects it in recovery mode (dfu). when it tries to restart the phone to start the restore, the iPhone will restart in recovery mode again (dfu). so itunes waits of the iPhone (even for many hours, and than doing nothing). the iPhone is always in dfu with black screen. - before changing the nand, it worked well I tried to reballing the nand, replace whith the old, but it is useless. always it stuck in dfu. I haven't lost any component. if I try to reset with power + home, it restarts dfu mode. I tried to remove the C1515 (i read another post where a user say remove or replace it to exit from dfu mode), but nothing .... always in dfu Now also with the old nand it remains in dfu how do I fix? the new and the old nand are properly read by the programmer, then work. sometimes in the various tests of resoldering (while trying to reprogram the new nand, replace the old, increase the thickness of the bulle .....) instead of absorbing 0.5a, it absorbed 0.05A - 0.03A .... . What may have happened? some short? some other component to remove, and then reballing and resolder? please help! thank's

03-23-2017, 04:31	#2 (permalink)
art83 Junior Member Join Date: Feb 2017 Posts: 9 Member: 2686964 Status: Offline Thanks Meter: 4	I post with more information.... If i connect it to a psu, it indicate the iphone absorb 0.48a (ok in dfu mode, but it stuck on this mode). One time, between the many test (when i remove, reballing and resoldering nand), the iPhone absorbed 0.03a immediately after 0.48a then 0.02a and again immediately after 0.5a.... all very quickly ... even one second between 0a and 0.5a I think the nand is welded well .... but I can not find the problem ... there are no shorts (otherwise it would absorb more) and still using a product were not shown. It's possible i need to reball baseband, or cpu (but is impossible i think... otherwise there is short, it is true?)?? Otherwise i try to change u2 ic???? Please help.....!!

03-25-2017, 03:29	#3 (permalink)
clashsndsstm Junior Member Join Date: Dec 2013 Posts: 17 Member: 2077894 Status: Offline Thanks Meter: 0	hello, have same problem, can you try restore with 3utools? which error you get? invalid serial nimber or smthng else?

03-25-2017, 22:01	#4 (permalink)
TBC01 Crazy Poster Join Date: Mar 2017 Posts: 57 Member: 2697189 Status: Offline Thanks Meter: 37	3utools will not restore neither will itunes, if the device is starting in HDFU and crashing it is because it cannot enter recovery mode when instructed. Even without a nand it should get to recovery mode at switch over, this on ipads requires battery voltage don't think power management will run so no RM. inspect at 40x mag I expect a disturbance of component or thermal shock under a local i.c.

03-27-2017, 01:17	#5 (permalink)
nombatca Junior Member Join Date: Jan 2009 Posts: 2 Member: 944542 Status: Offline Thanks Meter: 0	Reball the CPU! Noway other man.