We received an iPhone 6S with 4013 error
from our customer, we can see there is a trace of water. For this water-damaged
iPhone, mostly it's the problems of the iPhone motherboard. We need to
disassemble the iPhone 6S to check the iPhone motherboard.
After disassembling, measure the iPhone 6S
by DC power supply, the current is stuck at around 80mA, we
confirmed it is in data cable mode. Install the iPhone, and use iTunes to
restore it, but the fault is still there, the iTunes still reports unknown
error 4013.
Now we need to check the iPhone baseband
circuit, whether the iPhone baseband power supply is short-circuited, whether
the resistance value is normal, whether 19.2 clock is normal, we can replace it
with a better iPhone baseband CPU, and then restore the iPhone again, if the
restore process bar can move smoothly, then possibly it's the problem of the
iPhone baseband CPU.
Disassemble the iPhone, we found the area
around the iPhone baseband is corroded seriously; we suspected the iPhone
baseband power is damaged. Replace the iPhone baseband power, restore the
iPhone 6S, the fault still exists.
Remove the iPhone baseband CPU cover shield
by Titanium Alloy Tweezers, there is no traces of water around the
iPhone baseband, the iPhone baseband is good.
Put iPhone motherboard under the Stereo Zoom Microscope to observe, we found the screw hole BS0502
has been penetrated, there are several circuit lines in the lower layer board
are disconnected . Connect those broken circuit lines one by one, and then
install the iPhone.
Now use iTunes to restore the iPhone 6S
again, it succeed.
Summary: this 4013 error is not caused by a
iPhone baseband problem, it's caused by the penetrating screw hole causing the
iPhone CPU works abnormally.
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