[Android Q&A, Help & Troubleshooting] btsimonh:
Huawei (u8850) unbricked

I just wanted to relate my experiences in de-bricking this U8850 phone.

I installed 'Apps_2.6.35.7-perf+root+CWM_recovery 5.0.2.8' (firmware.nb0) using SUT to get CWM, and then installed Danile's 4.1.2

Good as far as it goes, but i could not for the life of me reproduce his kernel (my kernels are always unreliable), so after many days of playing, i decided to take the phone back to stock to see if i could reproduce the huawei stock kernel as a base to work on.

The problem was, how do you revert to stock; the phone was no longer recognised by SUT?

So I took a stock .nbo file and extracted the content (some java extractor found with google) in the hope that I could create a CWM flashable zip of the stock firmware.. a bit of research later, and i thought i had got the gist, put boot.img and system.img into a zip with a modified script file, and voila... a bricked phone.

At this point, i had CWM, but if the phone booted, it showed a flash of blue screen (I didn't know these ran windows ;) ), and back to huawei logo. Also I think i had to dismantle to disconnect battery to run CWM, as it's not available just on the volume-up-power restart.

So then I did more research, and came across QPST, Qualcom's tools. It seemed this should know something about the files i had extracted. I could not correlate everything in the extracted fileset with what QPST seemed to expect, but the first challenge was to get QPST and the phone talking. using various drivers, QPST would sometimes see it, sometimes not, but nothing good seemed to be coming from it. I returned to trying to get SUT to work on my brick; again, with some drivers it would connect, but a flash always resulted in Error 4000 - DEVICE_NOT_CONFIGURED.

Then I read somewhere that someone had found a driver change made SUT work, so i investigated drivers more.

What I found was that if i ran up CWM, I got two Huawei devices in XP for which I could not find drivers.

The devices showed up as VID_12D1&PID_1022&MI_00 and VID_12D1&PID_1022&MI_01.

I took the Huawei USB drivers folder, and copied the qcser.inf then changed entries under [QcomSerialPort] to match my VID/PID values.

(the two that had matching MI_ values).

On driver update, I had a serial port, plus something I'd not seen before - a USB storage device which contained the phone's partitions!!!

This certainly seemed promising... so into SUT again, same error 4000...

So the I tried QPST; and yes, it could see the phone. Scared to do anything to brick it further, I thought, ok, try some memory diagnostics.

On running the 'Memory Debug' tool, as soon as I tried to get a list, QPST said 'this phones in diagnostic mode, it must be in download mode to do memory diagnostics', but even better 'Do you want to set it into download mode now?'!!!!!

Yeah! click the button, and I see a screen I've only seen once before (and i don't know why last time), black, with a line added every few seconds... which from all my reading I know is a good sign.

OK, then I closed all QPST apps, and ran SUT.

This time, the firmware flashed no problem. Was a bit worried as boot time is long (but it was effectively 'first ever' boot for the phone).

I hope this helps someone else with this or another Qualcom based phone.

Basic lesson is:

If you see Error 4000, it may be that the phone is in diagnostic mode rather than download mode.

If you don't have drivers, or don't have the right drivers, check you VID and PID, and try putting them into the .inf file

QPST may have a simple use after all... to force a phone into download mode when SUT fails.