Root D855 recovery from bricked

[SimonMW]

OK, I am no noob at rooting, but have drawn a blank with this one. Would very much appreciate some advice.

I have 2 x LG G3 D855s, both running Cloudy G3 ROM. Both have been successfully downgraded to Android 4.4.2 (10L), rooted with purple drake, and Cloudy Lollipop installed. Perfect.

BUT whilst doing a Titanium restore on an app, one of them rebooted this evening, and is now bricked.

- Normal boot - never does anything other than initial LG boot logo;
- TWRP takes about 5 minutes on the splash screen before reaching the main TWRP screen (but has errors, see later);
- LG download mode only shows the initial logo on the phone but the PC does not 'see' it upon cable connection, and the phone never kicks into full download mode. Connecting my other d855 fires up download mode correctly, so PC drivers are OK.

Because download mode never fully starts, I am unable to restore to stock using the kdz / LG flash.

When TWRP DOES start, it is unable to mount /data, /cache, and the log has the following errors:

E: Could not mount /data and unable to find crypto folder
E: Unable to mount /data
E: Unable to recreate /data/media folder
E: Unable to mount /cache
E: Unable to mount storage
... etc.

Within TWRP Internal Storage is shown as (0MB), and /data and /cache are not mounted. My external_sd is mounted OK.

With TWRP running, a device is seen by my PC (Google Nexus ADB Interface) but 'adb devices' shows nothing. This is the same behaviour as the phone that works, so I assume that at least is normal.

I am unable to mount /data manually, or repair within TWRP.

With /data not mounted, I am unable to proceed any further...

So my question - how do I rebuild the screwed up partitions?

 

[SimonMW]

I tried today to enable fastboot instead of LG's download mode by overwriting laf from /dev/zero, to see if I can flash anything from fastboot. The first thing I did was write the existing laf to backup on external sd. That appears to have worked - the resultant file starts with:

ANDROID!È ž € Ææl ð à console=ttyHSL0,115200,n8 androidboot.hardware=g3 user_debug=31

So I figure that it has backed it up OK.

But when I run (in TWRP's terminal mode) dd if=/dev/zero of=/dev/block/platform/msm_sdcc.1/by-name/laf and reboot I still get the "download mode" starting icons, but the phone does not boot into fastboot, and "download mode" still doesn't work either.

At this stage I am ready (almost!) to just try and if=/dev/zero -> recovery to blow away TWRP and just RMA the phone, but if anyone has any advice it would be great :-D

 

[SimonMW]

Well it's kinda quiet in here... after seeing the great support given in other threads I was hoping for a little more than the deafening silence lol...

I'd RMA the phone, but at the moment even a dd if=/dev/zero of=/dev/block/platform/msm_sdcc.1/by-name/recovery accomplishes absolutely nothing - the phone still boots into recovery (TWRP) albeit after about 10 minutes and unable to mount /data.

What am I doing wrong, and how do I wipe the TWRP recovery partition from TWRP terminal (or wipe download mode so I can access fastboot)?