Update of 4th August (devel)

klh

Device must be running Android 9 (don't know if it still is)
Device must be unlocked (don't know if it still is)
Device musf be in Developer mode (can't switch to Developer mode)

None of those apply if you were on UT already (re-locking the bootloader is a manual step done in fastboot, so I doubt you did it by mistake). If you got an error message post the installer logs here (~/.cache/ubports/ubports-installer.log).

If you had to select your device manually then your PC probably didn't detect the device, so it probably wasn't in fastboot mode (unless it's one of the weird ones).

dtarrant

@klh
Ok, so tonight I tried again with Installer 0.9.5 and subsequently 0.9.6.
Managed to select recovery mode at one stage and also fastboot mode at another.
Also got firmware downloading message.
Things seemed to be getting progressively worse until I reached the situation where the Lenovo tablet is
un-responsive.
I am now completely stuck.
I have previously contemplated trying to install android 9 and re-building my system from scratch, but in view of my experience tonight, I wonder if even that will be possible.
Due to my inexperience, I never contemplated switching from devel to rc whilst the system was working.
I've learned the value of that advice the hard way.

klh

@dtarrant Going back to Android first might be the easiest - should all happen in fastboot so once you boot that it should be fine.

MrT10001

@dtarrant Yep, I would do what @klh has suggested. I have gone back to Android a lot to go forward on UT.

dtarrant

@mrt10001 @klh
My problem at the moment is that the Lenovo tablet is so screwed up that:
I cannot boot to the Lenovo splash screen;
I cannot launch fastboot;
None of the operations involving power/volume buttons work.

However, it's not completely dead. Various long presses of the power and volume buttons cause it to emit a haptic buzz. Sometimes the little red led at the top of the screen starts blinking as though it is still trying to load firmware.
I've tried charging it and I think connecting it to a power source provoked the little red led to start blinking.

My gut feel is that the tablet doesn't have a hardware fault, but that the firmware/software is in a complete mess.

For any chess fans, I feel as though I've been check-mated.
How can I re-set it and start a new game? I'm sure I can beat it next time!

Keneda

@dtarrant
What is the processor of this tablet ?
Isn't there a low level flashing tool for it like there is for madiatek ones (spflashtool) ?

MrT10001

@dtarrant Plug the device into the power and leave for a day. This should charge it to 100% and maybe you will get a splash screen (I have done this on many phones with "dead" batteries and it generally works).

If it works and you can get into fast boot, try TWRP recovery which is fantastic tool for recovery of a soft bricked device.

It is sometimes better to leave it for a day and come back with a different train of though.

dtarrant

@keneda
Processor is Qualcomm Snapdragon 450
Don't know anything about low-level flashing tools, but sounds interesting.
Thanks for the tip.

dtarrant

@mrt10001
Thanks for the suggestion. Tablet is charging now.
Don't know anything about TWRP. What can you tell me about it?

MrT10001

@dtarrant Read this on the XDA forums.

Be aware it is for the M10 TB-X605F or L which is denoted by F/L and not for the FL which has no forward slash, so it will work on your tablet (mine is the F version (no SIM slot) of F/L) just avoid Lenovo's silly and confusing derivative naming.

You obviously need to be in fastboot mode and flash it by using :

fastboot flash recovery <path to your  TB -X605F/L TWRP>

Once in TWRP, I highly recommend wiping the cache and data partition and then rebooting to the bootloader (i.e. fastboot mode).

Then try installing UT again. If UT fails to install reinstall the stock ROM and then follow the instructions to install UT again.

(For me this has turned a mediocre Android tablet into something a lot better and more interesting, it is nice having an Ubuntu 10" tablet..)

dtarrant

@MrT10001
Thanks for the information. Mine is the Lenovo TB-X605F.
Until the fatal update, it was working superbly with UT. I absolutely loved it! A great successor to my BQ Aquaris M10 running UT.
I so hope I can coax it back to life with the help of all the community members on this forum who have chipped in with advice and suggestions.

dtarrant

@keneda
So I did a web search for low-level flash tool for Qualcomm Snapdragon 450 and it led to XDA forums. Very encouraging!
But the YouTube video demonstrating the use of the tool was no longer available.
Another forum post said that the documentation for the tool was in chinese.
I also found a long rambling post by someone in the USA which was way over my head and concluded that this approach is a non-starter for me.

dtarrant

@mrt10001
Tried charging for a long period, but still unable to boot to Lenovo splash screen. Only faint haptic buzz and blinking red led.

Keneda

@dtarrant
First see this : https://en.wikipedia.org/wiki/Qualcomm_EDL_mode

Best (safer) chance would be to use Linux tool by Andersson : https://github.com/andersson/qdl

But yes, it seems to be way harder than with mediatek chips as qualcomm did not release any official tool...

~~I also found those :~~

~~https://repairmymobile.co/flash/qfil-tool-download/~~
~~https://qfiltool.com/~~
~~https://qpsttool.com/~~

~~But none of those are official from qualcomm, and i can't say that there is no risk using those, as www is a jungle full of predators lol.~~

Edit : didn't see the first time but on the wiki, there is this link that maybe is safer than the stricked three others, and could free your brick ^^
https://www.thecustomdroid.com/qpst-flash-tool-download-usage-guide/#what-is-qpst-tool

Again, not "officialy" from qualcomm.

dtarrant

@keneda
Wow, a mine of fascinating information. I will explore. This suggests it is possible to de-brick the Lenovo TB-X605F. All you need is to know stuff and have the right tools.
Many thanks

dtarrant

@keneda
Well, whilst browsing the stuff you linked relating to QPST (Qualcomm Product Support Tool), I came across a reference to EDL (Emergency Download Mode). The bricked device has to be in EDL mode in order to use the QPST tool.
Now here's the interesting bit: If your device has been bricked accidentally and just shows a black screen and vibrates, then it's probably already in EDL mode. Wow! This exactly describes the current state of my bricked Lenovo TB-X605F.
Sounds like the QPST tool is the way to go!

Keneda

@dtarrant
I hope you sorts this brick out ^^

Luksus

@dtarrant there is also the qdl tool for flashing stock image from linux.
See install section: https://gitlab.com/ubports/porting/community-ports/android9/lenovo-tab-m10-fhd/lenovo-x605#install

Maybe it is available in your distributions repository. Otherwise you would need to build it from source.

Keneda

@luksus yes i told him about QDL also ("Linux tool by Andersson")
Thanks for the install link ^^

dtarrant

@keneda @Luksus
After re-visiting the links you sent me, I am concerned some solutions required operations no longer possible on my bricked device. So, the best option is the QPST tool. This is a Windows-based solution and I have only Linux PCs. However, my 16yr-old grandson has a Windows PC, so I showed him the instructions and he is very comfortable with them. He kindly offerred to work the magic for me whilst he is waiting for his GCSE results! Result!!! I will keep you posted.

Update: 02 Oct
Still waiting for my grandson to be available to try this approach.