MC7455 9008 Device

[Bjørn Mork]

Aleksander Morgado <aleksander at aleksander.es> writes:
> On Thu, Jan 19, 2017 at 1:53 AM, Noah Taber <noahtaber at gmail.com> wrote:
>> https://sigquit.wordpress.com/2016/12/09/qmi-firmware-update-with-libqmi/
>>
>> Now I just need to get the colleague to learn basic linux... haha.
>>
>> If this doesn't work, any other suggestions?
>
> That should work. When in QDL mode (single TTY exposed) you can run
> the --update-qdl command and give it the firmware images (cwe+nvu) for
> the MC7455 as downloaded from Sierra Wireless' website. E.g.:

Maybe.  Let's hope so.

But I do fear that this modem is bricked beyond what we currently know
how to fix.  As noted, the "9008 mode" is well known from bricked
Qualcomm phones.  This appears to be the USB device ID of an earlier
bootloader stage. Maybe built into the chipset? See for example
https://github.com/openpst/sahara

If this is correct, then you might need to flash the Sierra bootloader
somehow before any of the Sierra images can be uploaded. Assuming they
are interpreted by that booloader.  But this is a lot of guessing, and
could be completely wrong as usual.  AFAIK, we don't have any docs on
this part of the process so it's all guesswork.

The good news is that it should be possible to debug and fix the modem.
The bad news is that you might need signed files we don't have... And if
whatever happened to the modem has erased the RF measurement data, IMEI
and other important data, then you could be in for an "interesting"
experience trying to restore those.

The probability of fixing the problem depends largely on what has
happened to the modem.  If it is just the booloader falling back to a
debug mode as a failsafe, then it could be "easy" to fix.  It will help
to know *how* the modem ended up like this.  And if you can share that
information, then it will at least help others avoiding similar problems
even if we cannot fix your modem.

I must admit I'm a bit curious, as I've found these modems to be pretty
robust against all sorts of weird things a user can do.  Now, I haven't
actually tried overwriting critical parts of the flash, but the fact
that I cannot even read those parts in application mode is a good sign
of protection.



Bjørn