[General Topics] twelfth:
To flash these images, you will need to use Fastboot. If you don't already have Fastboot installed, you can install Minimal ADB and Fastboot from this thread: https://xdaforums.com/showthread.php?t=2317790

System Images

These are raw, stock, flashable in Fastboot only images. If you already have a custom recovery installed, then you can use that to flash these images instead. Bear in mind that flashing recovery.img while in recovery will replace your custom recovery with stock recovery.

The device ships with version R313.

persist.img : https://www.androidfilehost.com/?fid=745425885120742754

persist.img : md5 : 682275ff830598fa42a05250002cc02f

splash.img : https://www.androidfilehost.com/?fid=961840155545573563

splash.img : md5 : 1d56e5e62f27baf837084165694db52c

boot.img : https://www.androidfilehost.com/?fid=961840155545573562

boot.img : md5 : fe044e9ca9ccf7bdc4819500cfbffcda

recovery.img : https://www.androidfilehost.com/?fid=889764386195907755

recovery.img : md5 : 6b3b9e3b171a8f1151a60ae14e410b93

system.img : https://www.androidfilehost.com/?fid=745425885120740418

system.img : md5 : 4f6fef214ed162d921c85c5369f3454d

Version R403:

persist.img : https://www.androidfilehost.com/?fid=673368273298965596

persist.img : md5 : 10f983ad12dcf8452527bef513951ea5

splash.img : https://www.androidfilehost.com/?fid=817550096634777452

splash.img : md5 : 1d56e5e62f27baf837084165694db52c

boot.img : https://www.androidfilehost.com/?fid=745425885120740107

boot.img : md5 : e1d7f8875afb3a4a00602890a5b94ee7

recovery.img : https://www.androidfilehost.com/?fid=745425885120740108

recovery.img : md5 : 1d4da69e929119e85c68117fadc0484f

system.img : https://www.androidfilehost.com/?fid=817550096634777453

system.img : md5 : 7078ca8cd3ba8b7ba4e5baa94112e570

Version R412 is currently the latest version for the device:

persist.img : https://www.androidfilehost.com/?fid=817550096634780185

persist.img : md5 : 40e0e812ea0645fcd46c3136dc8f85a9

splash.img : https://www.androidfilehost.com/?fid=817550096634777468

splash.img : md5 : 1d56e5e62f27baf837084165694db52c

boot.img : https://www.androidfilehost.com/?fid=889764386195907458

boot.img : md5 : dac5a75fa41ddfe9da9186ea475ed707

recovery.img : https://www.androidfilehost.com/?fid=889764386195907459

recovery.img : md5 : 71aed500e670b7a81d6a7a43b7ae9ed0

system.img : https://www.androidfilehost.com/?fid=817550096634777469

system.img : md5 : a5b5001f9417ccc7e237661a01b2da38

How to flash:

1) Download all of the files for the version you want to flash.

2) Power off the device completely.

3) Enter fastboot mode by holding down the M-Button top of the phone and then holding down power until "FASTBOOT MODE" screen shows up.

4) Connect your phone to your computer. (This assumes you already have Fastboot and ADB installed and generally know how these tools work)

5) Use fastboot to flash each of the images to the correct partition: eg,

fastboot flash persist KB15_3_R403_160608_persist.img
fastboot flash splash KB15_3_R403_160608_splash.img
fastboot flash boot KB15_3_R403_160608_boot.img
fastboot flash recovery KB15_3_R403_160608_recovery.img
fastboot flash system KB15_3_R403_160608_system.img

6) Reboot.

First boot after flashing the system images will take some time as "Android is upgrading..." If you flashed version R412, you will be on the latest version. The older versions are provided for those who may have preferred them.

Custom Recovery

Before you install this recovery, it is very important to know that you

MUST NOT

let TWRP install SuperSU.

Download the latest TWRP from here: https://twrp.me/devices/marshalllondon.html

Older/Test build:

TWRP v3.1.1-0 : https://www.androidfilehost.com/?fid=745425885120740158

TWRP v3.1.1-0 : md5 : 05e61cbeb1afbc479d85f260acf52d3e

1) Download the TWRP image linked above.

2) Power off the device completely.

3) Enter fastboot mode by holding down the M-Button top of the phone and then holding down power until "FASTBOOT MODE" screen shows up.

4) Connect your phone to your computer. (This assumes you already have Fastboot and ADB installed and generally know how these tools work)

5) Use fastboot to flash:

fastboot flash recovery Marshall_London_TWRP_3_1_1-0.img

6) When fastboot is done, DO NOT reboot. Doing a fastboot reboot or fastboot reboot-bootloader will cause the system to overwrite TWRP with stock recovery. Pop the battery out instead.

7) Feel free to boot into recovery at this point to root or make backups. (Volume Wheel + Power for 4 seconds after you feel the power on buzz)

Rooting

Whatever you do, DO NOT allow TWRP to install SuperSU/Superuser/Root. Your device will fail to boot.

You

must

use Magisk. Magisk is systemless root and does not result in files being installed in /system, preventing the hang on boot.

1) Download both the Flashable ZIP and Magisk Manager APK.

2) Put both the ZIP and APK on a MicroSD card.

3) Turn off the phone, put the MicroSD card in.

4) Boot into TWRP Recovery by holding volume wheel down and power button down for about 4 seconds after you feel the power on vibration. Release the buttons.

5) TWRP Splash screen should pop up. Swipe to allow write.

6) Press "Install", "Select Storage", "Micro SDCard", "OK", scroll down to find Magisk-13.3.zip, press the file name and them Swipe to confirm Flash.

7) Reboot.

8) Once booted, you will need to use a file browser app, like Explorer by Speed Software, to find MagiskManager.apk on your MicroSD and install it. (Why? Cause it was removed from the Play Store.) This will require that Unknown Sources is enabled under Settings/Security.

---

Edit for 2021:

I have revived my London for some projects and ran into some issues trying to use modern methods/versions for the device.

I wanted to upgrade what I could and using Magisk v23 on the boot.img bootloops the device. I tried some lower Magisk versions and was met with the same result... so instead of fiddling with it I went back to my known working config on my second London and ripped the files to fix my first device.

As such, it is

HIGHLY

advised that you stick with v13.3 (known working version on both of my devices) for the image and v5.1.1 for Manager.

The necessary files for this config have been mirrored here:

Modified Marshall London R412 Boot Img with Magisk v13.3 (no recovery) applied:

https://www.androidfilehost.com/?fid=14943124697586343614

MD5: 23426a4a1d82f9a7465ba9a7cdf30e1f

Magisk Manager v5.1.1:

https://www.androidfilehost.com/?fid=14943124697586343616

MD5: 790c9d412e7afbd76566ee47f24cd3b8

To flash:

From a power-off state, hold M-Button and Power until "FASTBOOT MODE" shows up on the screen.

Connect phone to PC

"fastboot flash boot MLondon_Magisk_Boot.img"

You *MUST* be on Lollipop version R412 for this boot image.

This now means that if you are on version R412, all you need to do is flash the modified boot.img file to root your device instead of flashing recovery and applying the Magisk.zip inside TWRP. I do not have fastboot flashable files for the last firmware version for the Marshall London (titled "Tom Petty").

The alternative, of course, is to use TWRP and go through the steps listed above, but honestly, I've found TWRP to be largely unnecessary when you already have a Magisk patched boot image. This all is just being put here to preserve a working config.