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[GUIDE][BOOTLOADER,TWRP, ROOT]Lenovo TAB3 8/TB3-850F

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Hi mate. Not solved yet. It's not a huge problen but it's one of those things that has me wondering why. I am so excited to try the Lineage you are teasing us with above. Sounds fantastic!
Coo. Yeah I'm wrapping things up on the LineageOS 14.1 ROM. I ran into some buggy behavior on the system-wide dark mode feature I added, so I've undone all of that and resorted to good old-fashioned deodexing and per app theming with an overlay manager. This way is much nicer in terms of UI aesthetics, and won't cause stability issues like my previous implementation. While LOS 14.1 does natively support USB OTG protocol, I am adding custom OTG drivers for
 
Hi mate. Not solved yet. It's not a huge problen but it's one of those things that has me wondering why. I am so excited to try the Lineage you are teasing us with above. Sounds fantastic!
I'm wrapping things up on the LineageOS 14.1 build. Had to resort to another tactic on my added dark mode feature, but it'll be better in the long run. While LOS 14.1 does natively support USB OTG protocol, I have added custom OTG drivers for added filesystem support; exFAT (R/W), FAT32 (R/W) and NTFS (R). This effectively forces recognition and accessibility on OTG storage devices which have been formatted and configured on a Windows PC, for example, and would not normally be supported by Android's native OTG implementation.
 
Hi mate. Not solved yet. It's not a huge problen but it's one of those things that has me wondering why. I am so excited to try the Lineage you are teasing us with above. Sounds fantastic!
I am having some major difficulties with the XDA app as well as the XDA web-based user interface. I either cannot get my posts to add to the thread, or they will be duplicated and post multiple times. I have the app on 8 different devices and the result is always the same. When creating posts or threads, the cursor freezes and sticks, resulting in a huge effort to type even a single word. I made a post here earlier today -- which I do not see now -- that was a small paragraph, but took me nearly one hour to complete. I'm typically very calm and sedate, but my patience gets quickly unravelled on this XDA issue. Reaching my boiling point, I took my Tab3 8 and pummelled the floor with it until the logic board actually came through what was left of the digitizer assembly. While this was very therapeutic for my built up stress with this app, it does create a bit of a holdup on my LOS 14.1 project, which I was actually wrapping up. I am going to order another device and see what I can figure out about getting the XDA app to work. I may also need to get another device just for it. I'm on the web-based interface now and it's not much better. I will keep my progress posted. Thanks guys for your support.
 

comfortable

Senior Member
Jan 9, 2013
92
24
I am having some major difficulties with the XDA app as well as the XDA web-based user interface. I either cannot get my posts to add to the thread, or they will be duplicated and post multiple times. I have the app on 8 different devices and the result is always the same. When creating posts or threads, the cursor freezes and sticks, resulting in a huge effort to type even a single word. I made a post here earlier today -- which I do not see now -- that was a small paragraph, but took me nearly one hour to complete. I'm typically very calm and sedate, but my patience gets quickly unravelled on this XDA issue. Reaching my boiling point, I took my Tab3 8 and pummelled the floor with it until the logic board actually came through what was left of the digitizer assembly. While this was very therapeutic for my built up stress with this app, it does create a bit of a holdup on my LOS 14.1 project, which I was actually wrapping up. I am going to order another device and see what I can figure out about getting the XDA app to work. I may also need to get another device just for it. I'm on the web-based interface now and it's not much better. I will keep my progress posted. Thanks guys for your support.
Sorry to hear about the tablet!

I know the feeling. I have had a fair share of editing text frustrations on xda (I haven't tried the app yet). Please just take your time if you decide to get a new device to finish things off. No dramas if you decide not to.

Sidenote:
One of my best experiences has been with LineageOS on the samsung galaxy s5 due to the support for other filesystems (which you spoke about earlier). I guess LineageOS dropped support due to licensing?
 
Sorry to hear about the tablet!

I know the feeling. I have had a fair share of editing text frustrations on xda (I haven't tried the app yet). Please just take your time if you decide to get a new device to finish things off. No dramas if you decide not to.

Sidenote:
One of my best experiences has been with LineageOS on the samsung galaxy s5 due to the support for other filesystems (which you spoke about earlier). I guess LineageOS dropped support due to licensing?
I needed a new device anyway. I have a refurbished 850f en route. The one I got a few months back was used and had considerable wear. The volume rocker was in the mid stages of giving out as well. On filesystem standards and licensing, the subject matter gets rather complex. Keep in mind that, while Android has long supported USB OTG, it has never officially supported NTFS or exFAT. Still to this day, the NTFS filesystem is not supported by AOSP., while exFAT is supported only on some newer devices. Certain device manufacturers, such as Samsung, have added such support via their custom Android overlays like Samsung Experience and One UI. Huawei done the same thing with EMUI and more recently with HarmonyOS 2.0. Samsung was also known to add native support by way of firmware implementations on some devices.
The legal waters on this topic are extremely muddy. It appears that some companies and corporate entities interpret the licensing and fair use guidelines differently, resulting in a vast disparity regarding native support of these filesystems. Some companies will, while others won't entertain the notion. Many Android file explorer apps now include native support for these filesystem standards. MiXplorer is a good example, as well as a file explorer by Paragon Software.
 
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comfortable

Senior Member
Jan 9, 2013
92
24
I needed a new device anyway. I have a refurbished 850f en route. The one I got a few months back was used and had considerable wear. The volume rocker was in the mid stages of giving out as well.
Oh :)

On filesystem standards and licensing, the subject matter gets rather complex. Keep in mind that, while Android has long supported USB OTG, it has never officially supported NTFS or exFAT.
I have noticed this whenever I have tried to download a linux iso of 4GB+ on storage using fat32
Still to this day, the NTFS filesystem is not supported by AOSP., while exFAT is supported only on some newer devices. Certain device manufacturers, such as Samsung, have added such support via their custom Android overlays like Samsung Experience and One UI. Huawei done the same thing with EMUI and more recently with HarmonyOS 2.0. Samsung was also known to add native support by way of firmware implementations on some devices.
The legal waters on this topic are extremely muddy. It appears that some companies and corporate entities interpret the licensing and fair use guidelines differently, resulting in a vast disparity regarding native support of these filesystems. Some companies will, while others won't entertain the notion. Many Android file explorer apps now include native support for these filesystem standards. MiXplorer is a good example, as well as a file explorer by Paragon Software.


Good info. In my opinion better file system support is one of those critical things that's just never talked about. Thanks for your work.
 
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Oh :)


I have noticed this whenever I have tried to download a linux iso of 4GB+ on storage using fat32



Good info. In my opinion better file system support is one of those critical things that's just never talked about. Thanks for your work.
My Tab 3 8 is due to be delivered this Friday. I could have probably finished up without having a device, but I have building blind. Testing is crucial to me.
Out of curiosity, which variant of the 850F do you have? The 80 or 81 HW variant? On the back of your device will be a manufacturer's sticker with your serial number printed on it. At the end of the serial number, you will see either an 80 or 81 within parentheses...(80) or (81).
 
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comfortable

Senior Member
Jan 9, 2013
92
24
My Tab 3 8 is due to be delivered this Friday. I could have probably finished up without having a device, but I have building blind. Testing is crucial to me.
Good policy. Take all the time you need to test.
Out of curiosity, which variant of the 850F do you have? The 80 or 81 HW variant? On the back of your device will be a manufacturer's sticker with your serial number printed on it. At the end of the serial number, you will see either an 80 or 81 within parentheses...(80) or (81).
My 850F is the 80 variant.
 
Did they improve anything?
Seems to be an insignificant difference in board platforms. The (80) variant has the MediaTek mt6735m SoC, while the (81) variant has the MediaTek mt8161p. The kernels on both variants, however, are compiled for the mt6735m. The two platforms are virtually identical in terms of specs.
I got my new 850F yesterday, so I'm back at it again.
 
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limited_imagination

Senior Member
Nov 2, 2013
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Seems to be an insignificant difference in board platforms. The (80) variant has the MediaTek mt6735m SoC, while the (81) variant has the MediaTek mt8161p. The kernels on both variants, however, are compiled for the mt6735m. The two platforms are virtually identical in terms of specs.
I got my new 850F yesterday, so I'm back at it again.
I haven't visited this thread in a long time, having moved on to a Mi Pad 4 to replace my TB3-850F.

But it's really cool to see you pick up the baton on this.

You now know four people with an (81) variant... add me to the list.

Mine has a manufacturing date of 2017-04-10 on the sticker.

I look forward to testing your new build!
 
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I haven't visited this thread in a long time, having moved on to a Mi Pad 4 to replace my TB3-850F.

But it's really cool to see you pick up the baton on this.

You now know four people with an (81) variant... add me to the list.

Mine has a manufacturing date of 2017-04-10 on the sticker.

I look forward to testing your new build
Thank you for your words of encouragement. I've found out that, not only are there two hardware variants to the 850F, but there are also some regional variants as well. Lenovo and Motorola have long been known to push the envelope on device variants, a tactic that has greatly broadened their global marketing of mobile devices. I am currently making bids on a 850M on eBay. If I can snatch it up at a decent price, I'm curious to see the difference between the two Tab3 8 models (other than the 850M's GSM support).
Anyway, thanks to you, @limited_imagination, @pndwal, @comfortable, and all you guys who made me feel invited here. This is the true spirit of the custom Android community. I see no roadblocks in the way for having my LOS 14.1 build posted by this weekend. I have heard from the original OP of the existing LOS 14.1 thread. He has given his blessings for my contributions as well as permission to take over his original thread. I am getting with a moderator to try and make that happen.
 
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yurais

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Feb 10, 2008
329
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the google drive link is not working... could someone upload this to androidfilehost ?
 
Folks I haven't jumped ship or anything. The worst aspect of a port ROM is that any development puts you in the role of cleaning up messes and fixing the errors of the handful of people who have worked on it previously. When going to put the ROM back into its default mode of SELinux enforcing, I have system apps crashing all over the place. So bad, in fact, that I booted Safe Mode to try and duplicate the crashing episodes in am emulated runtime environment.
 
Greetings. Okay I seem to have broken my first rule of thumb when staring on this project: NEVER ASSUME ANYTHING. So I assumed that the LOS 14.1 ROM was integrated with a LOS boot image. Had I read the threads a little more thoroughly, I could have saved myself a ton of trouble. As you guys probably already knew, this is a dirty port hybrid boot image, with a LOS ramdisk and a stock Lenovo kernel. My trouble with SELinux enforcing, merged changes and force closing crashes have now come to light. (I do have to assume that either (1) Lenovo never released the kernel source code for the Tab3 8, or (2) nobody has sat down and actually compiled a kernel from source.) I had to go back to the drawing board on a large sum of my work. I just wanted to give an update and apologize for my huge oversight. Now that I have a full perspective of everything, I feel confident that things will go a little smoother. Plus, this will give me a base template for porting other custom builds. Our present kernel, 3.18.19, supports Android 6.0 all the way up to Android 10.
Anyway I'm elbows deep once again. Wish me luck....
 
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    Greetings. Okay I seem to have broken my first rule of thumb when staring on this project: NEVER ASSUME ANYTHING. So I assumed that the LOS 14.1 ROM was integrated with a LOS boot image. Had I read the threads a little more thoroughly, I could have saved myself a ton of trouble. As you guys probably already knew, this is a dirty port hybrid boot image, with a LOS ramdisk and a stock Lenovo kernel. My trouble with SELinux enforcing, merged changes and force closing crashes have now come to light. (I do have to assume that either (1) Lenovo never released the kernel source code for the Tab3 8, or (2) nobody has sat down and actually compiled a kernel from source.) I had to go back to the drawing board on a large sum of my work. I just wanted to give an update and apologize for my huge oversight. Now that I have a full perspective of everything, I feel confident that things will go a little smoother. Plus, this will give me a base template for porting other custom builds. Our present kernel, 3.18.19, supports Android 6.0 all the way up to Android 10.
    Anyway I'm elbows deep once again. Wish me luck....
  • 12
    This guide, for the Lenovo Tab 3 8" (TB3-850F), has 3 purposes:

    1. Unlocking your bootloader;
    2. Installing TWRP custom recovery;
    3. Attaining superuser privileges (root) of the stock OS.

    NOTE:
    I can attest & confirm that this method has worked 100% on at least 7 devices of my own. Please read and re-read the instructions carefully before proceeding. If you follow this tutorial exactly as delineated, you should have no adverse issues in unlocking your bootloader, flashing custom recovery, or achieving systemless root of the stock Android OS.




    MENTIONS & THANKS:
    Based on XDA Senior Member @Hemphiz's groundbreaking root and custom recovery for this device, I am now revising this thread wth improved step-by-step instructions based on members' feedback and experiences. Thanks @Hemphiz for your research, assimilation of necessary files, and for breaking ground on this tablet. Thanks also for your granting me ownership of the thread. Your contributions are greatly appreciated by many. Thanks to the great @Chainfire for his flashable systemless rooting script. Thanks to @jemmini for compiling TWRP for this tablet. Finally, thanks to the many members who have tested this guide and provided much needed input & user experience.

    DISCLAIMER: As always, please be reminded of the risk involved with flashing a custom recovery and/or attempting to attain superuser privileges of your Android OS. I will not be held responsible for devices bricked or otherwise rendered inoperable as a result of this thread. You assume full responsibility for any good or bad which may result from proceeding any further. However, with that having been said, I will provide any and all support possible. Read and follow the foregoing steps thoroughly and carefully prior to proceeding. NOTE: THIS GUIDE IS INTENDED ONLY FOR THE LENOVO TAB 3 8"/TB3-850F.

    REQUIREMENTS:

    1. Minimal ADB & Fastboot v1.4 (or newer) Windows Installer;
    2. Windows PC or laptop (Mac may be used; however this guide is intended for Windows 7 and newer operating systems);
    3. Official Lenovo USB Device Driver v1.1.21;
    4. TWRP v3.0.1 for the TB3-850F;
    5. ADB Driver Installer for Windows;
    6. SuperSU v2.82-SR5 flashable zip.

    (All files, drivers & utilities for this process are available in the below download link)

    DOWNLOAD LINK: https://drive.google.com/folderview?id=1l-YN5aXmjDF3O1bHxFHVIxLKuvd847Q9




    INSTRUCTIONS:


    1. First and foremost, unlocking the bootloader is necessary. Also, this step is a good place to make some requisite preparations. Power on your Tab 3 and select SETTINGS once booted up. Go to ABOUT DEVICE, find BUILD NUMBER, and tap it 7 or 8 times until DEVELOPER OPTIONS is enabled. In DEVELOPER OPTIONS, tick OEM UNLOCKING and USB DEBUGGING. On your PC, install the Minimal ADB & Fastboot utilities, the ADB Driver Installer, and the Lenovo USB Driver Installer. Connect your Tab 3 to your PC with the supplied (or quality equivalent) OEM charging/syncing cable. Open a command window in your ADB/Fastboot directory, by holding SHIFT and right clicking in the desired path. In the command window, type: adb devices & press RETURN. If your device is connected properly, the command window will display a string of numbers/letters, which represent your device's serial number. If your serial number does not appear in the window, try changing USB ports, change syncing cables, or try reinstalling the ADB Drivers. Once properly connected, type adb reboot bootloader & press RETURN. Your tablet should boot into Fastboot Mode, which will be displayed in white bold letters on your device's display once complete. Once in Fastboot Mode, type fastboot oem unlock & press RETURN. Your device will prompt you to press Volume Up to proceed with unlocking the bootloader, or Volume Down to cancel the process. WARNING: UNLOCKING THE BOOTLOADER AUTOMATICALLY INITIATES A FACTORY DATA RESET. YOU WILL LOSE ANY UNSAVED VIDEOS, MUSIC, PERSONAL FILES, ETC.

    2. Now that your bootloader is unlocked, you are ready to flash TWRP. Download the twrp.img file from my link and save it to your PC in the ADB/Fastboot path/directory. Also, save a copy of the file on your device's internal storage or external micro SD card. Since your device underwent a factory data reset, you will again need to enable DEVELOPER OPTIONS & tick OEM UNLOCKING & USB DEBUGGING as you did in Step 1. When you have done this, again open a command window, ensure a proper connecion, & type adb reboot bootloader & press RETURN. Once in Fastboot Mode, type fastboot boot twrp.img & RETURN. EXTREMELY IMPORTANT NOTE: this device's boot image is secured with dm-verity. Leave the /system partition as read-only when prompted by TWRP. Mounting /system as read/write at this point will result in a boot loop. Flashing SuperSU, as outlined in Step 3, will patch dm-verity and fix this.
    From the TWRP main menu, select INSTALL, select the image file option in the bottom right of the screen, navigate to the location where you saved twrp.img in device storage or external storage, and commence the installation. Be certain and correctly choose "recovery" when prompted by TWRP. Now select REBOOT, then RECOVERY. Your TWRP custom recovery should now be successfully installed on your device's /recovery partition.

    3. Now, it is time to root this tablet. Download & save a copy of the SuperSU v2.82-SR5 zip file to the tablet's internal or external storage. In TWRP main menu, select INSTALL & navigate to the saved SuperSU zip. Commence with installation. Systemless root mode will unpack, modify, repack and flash the patched boot image. Once done, reboot system. Your Android OS should now have full systemless root, and the /system partition may now safely mount as read/write.

    TROUBLESHOOTING:

    In the event your device becomes stuck in a bootloop, or is otherwise failing to boot into the OS, the following is a link to my stock firmware images thread for this device. NOTE: the following link will be beneficial only if your device successfully boots into Recovery/Fastboot mode. This link provides stock partition images of /boot, /recovery, /logo & /system. Typically, flashing the stock boot & system images will get you up & running again, and will restore the Android OS to stock condition.
    https://forum.xda-developers.com/an...o-tab-3-8-tb3-850f-android-6-0-t3593043/page5

    In the unfortunate event that you encounter a brick (your device fails to boot into the OS or Recovery Mode), please visit @r&xp's thread on unbricking your device & restoring it to factory stock condition. Members using his thread be sure to thank @r&xp. His collection of necessary files & comprehensive instructions has saved many, many bricked tablets. https://forum.xda-developers.com/android/help/lenovo-tab-3-8-tb3-850f-unbrick-root-t3598727
    5
    News Flash for users of TB3-850F!

    We now have stable LOS14.1 for TB3-850F! :)

    See post above. Regards, PW.

    Alerting:
    @Hemphiz
    @Lister Of Smeg
    @mtpc
    @stonedpsycho
    @fran89
    @r&xp
    @john3voltas
    @Garcy23
    @voland34
    @DeblaGaming
    @sorun343
    @limited_imagination
    4
    Yeah, I'm not sure how I screwed it up but I'm glad it's working. In order to get into adb I tried the method you mentioned of holding the volume+ for 5 seconds and then plugging in the usb cable. From there I used adb to reboot into the bootloader. I tried flashing the boot and recovery images from there, but it didn't seem like they took. So then I used the fastboot boot command with the TWRP image, but it wouldn't let me access the data partition for some reason. I went to reboot and then all hell broke loose and it was just rebooting through TWRP failing with openscript and then rebooting again nonstop. I couldn't manage to shut it off completely even holding the power button for 30 seconds or so. I figured I was screwed, but held the volume up, volume down (and I think power?) at the same time and suddenly it actually launched TWRP. However, it couldn't access the data partition for some reason. I threw the stock boot, recovery, and system images on an SD card and then flashed them all and that finally got it working.

    I've rooted other phones, but I've had hardly any experience with adb. Fortunately I feel like I did learn quite a bit from screwing up, which is always a plus.
    Great work. Sounds like a good learning experience for you also. These devices on a MediaTek platform are a horse of a different color indeed. I've bricked a good handful of these devices through trial & error myself. By the way, please be sure and hit the thanks button on the OP. @Hemphiz done an excellent job initiating TWRP & root for this great budget tablet.
    I am currently working on a stock based 6.0.1 ROM for this device: rooted, deodexed, debloated & zip aligned. I'll add a few baked-in features like Substratum & Viper4Android. Also I'll add a couple of tunable governors & tweaks to the stock kernel. I'm terribly tied up at work, resulting in having to take a couple weeks break from Android, but I should be up & running again in 3 weeks or so.
    Anyway, I'm very glad it worked out for you. Try this to iron out any bugs with booting TWRP. First, save a copy of the twrp.img to your internal storage or external micro SD card. Next, get your device into TWRP. Select INSTALL, then select the flash img option in the bottom right-hand corner. Navigate to the location of your TWRP.img, commence to install and select "RECOVERY" when prompted to do do. Once done, wipe Cache & Dalvik/ART. Reboot system. This should allow smooth booting of TWRP, with no loops or lags.
    4
    my tablet is tab 3-850f_S100030_161209_row

    so i guess it could be possible to root...i am little be afriad to do that...

    this step 6

    #6 Now you need to boot to your custom recovery via the button combo for the device. (imo this tablet is a pain to boot into recovery compared to most devices) power off the phone. Wait a few seconds. Now hold the power button - then while still holding the power button press Volume up and then Volume down. Hold it for about a second then let them all go. If it worked then you will get the usual boot logo followed by the main twrp screen. Swipe to allow it to make modifications. If it boots into the Chinese recovery thing then just turn it off and try again. I would suggest getting an app that allows you to "reboot to recovery" once your all done and rooted. For root. Simply put the "Supersu sr3" zip in the storage of your tablet. Then flash it via twrp. "install - find where you put the zip - flash - reboot system" Done.

    would someone be more specific to explain...i get my tab in boot mode with holding power buton and volume down an up......and in display is simbol of android with mesage no command..its confused me...

    ---------- Post added at 01:45 PM ---------- Previous post was at 01:28 PM ----------

    i found a solution...press power button 2 seconds and quick press once volume up....

    now i am in recovery boot menu...

    so if someone to explain more specific this step 6

    thanx for advices

    regard

    See this post from Lister of Smeg's TB3-850F Thread, re root & recovery for TB3-850F. Note 'To Enter TWRP':

    filedropper.com/tb3850froot (for files)
    Quote:
    Originally Posted by mtpc
    Hey guys, It's me again. I managed to crack down the russian CAPTCHA and downloaded those files, and it just WORKS! I now have full root on my TB3-850f. I wrote down simple HOW-TO:
    [Slightly ammended by Peter Wallace (Original Post #49)]
    1) Copy SuperSU-v2.79-SR1-20161221223537.zip to the tablet
    2) Enable developer and USB debugging
    3) Open cmd (command Window) in folder with ADB and FASTBOOT
    4) Type these commands:adb reboot bootloader
    Then:fastboot oem unlock
    5) Hold down power button and reboot. Repeat 2) and enable OEM UNLOCK
    6) Repeat 3) and type:adb reboot bootloader
    7) then type:fastboot boot recovery.img (must be copied in the same folder as adb.exe and fastboot.exe)
    (Don't flash recovery yet - system will replace stock recovery before you have root)
    8) Use TWRP to install SuperSU. - Now you have ROOT (Systemless) (can update to SR3, etc)
    9) Repeat 3) and type: adb reboot bootloader
    10) Type:fastboot flash recovery recovery.img - Now your new TWRP recovery will be permanent.
    11) Use TWRP to reinstall SuperSU as lost in step 10 - Now you have ROOT (Systemless).

    To Enter TWRP:
    After powering down, press power, wait 1 sec then hold both vol up & down also (all 3 buttons) until vibrates.

    I also uploaded the files here: filedropper.com/tb3850froot

    Peter W:
    Here is link to latest 850f rom:
    http://lenovo-forums.ru/files/file/1549-lenovo-tab3-a8-tb3-850f_s100030_161209_row/
    Which takes you to https://cloud.mail.ru/public/8T5R/RWCkuBz19
    4
    Thanks for the guide!
    Everything works but when I reboot into recovery I just get the dead android with no command under him..
    I tried two times with same result Fastboot reports twrp flashes ok

    Any ideas?

    Thanks
    Not to hijack the OP's thread but here are my thoughts. The dead Android indicates that TWRP did not successfully flash to your /recovery partition. Sounds like stock recovery is still installed. First, place a copy of twrp.img on your device's internal storage or on an external micro SD. Try this: instead of typing the command "fastboot flash recovery twrp.img", type " fastboot boot twrp.img" (assuming your twrp file is named twrp.img. If it isn't, rename it twrp.img for simplicity purposes). This command will temporarily boot your device into TWRP recovery. From the main menu on TWRP, select INSTALL. In the bottom right of the screen, select the option for "img" files. Navigate to where you stored "twrp.img" and select it. Install it to "RECOVERY" when prompted. Once it flashes, select REBOOT then select RECOVERY. Your device should now successfully boot into TWRP recovery.