Hi DS!

> Looking at the project in Altium, it seems the signal trace from D5 to
> U201 sits at the bottom layer.

Do you have the ability to run Altium and open the PcbDoc natively?
If so, highlight the net named FDP.  I don't have the ability to run
Altium myself (no Windows), but looking at the Gerber files in gerbv,
I see that the trace from U301-D5 goes to a microvia right next to the
ball, then on L7 it immediately goes to another microvia to L6, on L6
the trace goes to the area underneath U201, and then it goes through
another pair of microvias back to the surface, coming out right next
to U201 ball F4.  Thus the long part of the trace is on an inner layer
(L6), and the only parts that come out to the surface layer are the
tiny runs on each end between the ball pad and the microvia, each
completely under the respective IC package.

Please double-check on your end - perhaps you were looking at a
different signal?

> I think it might be not too difficult to
> do some surgery to cut the trace in the middle and pull it up elsewhere.

I don't see how the trace cutting can done anywhere other than in the
very short L8 (surface) run under U301 (requiring removal of that IC
with a BGA rework station); cutting the trace at that point would be
doable, but I don't see any way to pull up the U301-D5 side of the cut

> BTW is there an easter egg in the PCB layout? I can read "TimLee Allen
> Shawn Jean Shanny" above the SIM holder.

These names/signatures made out of microvia patterns have been
preserved from Openmoko.  It appears that back in the days of Openmoko
HDI PCB microvias were made by some different process compared to how
they do it nowadays, and on OM's original GTA02 boards these microvia
patterns (names/signatures) are actually visible with the naked eye on
the finished product boards, on the side with the display.  When my
Iranian contacts made the FCDEV3B layout from OM's GTA02, they kept
OM's names/signatures (fairly so, as we are using the modem layout
which is originally OM's), but they were moved to a slightly different
location, which is where you see them now.  But they are no longer
visible on the finished board (except perhaps via X-ray) because
today's PCB fabs make these microvias in some different way that
results in them being invisible.

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