[Samsung Galaxy Tab A series Guides, News, & Discus] MossyTC:
The purpose of this thread is to have one post with links to all of the following guides:

Unlock Bootloader by [MENTION=303482]mingkee[/MENTION]

TWRP Recovery by [MENTION=903232]Magendanz[/MENTION]

Custom ROM Nexus Stock by [MENTION=903232]Magendanz[/MENTION] - current release is SM-T510 only

Custom ROM LineageOS 16.0 by [MENTION=903232]Magendanz[/MENTION] - SM-T510 only

All credit to [MENTION=903232]Magendanz[/MENTION] and [MENTION=303482]mingkee[/MENTION] for those.

Below are my own observations which supplement but do not replace the guides above. The original posts includes important information not quoted below. You need to read the relevant guides above (depending on what you want to do), and you may get some additional benefit from reading my thoughts below before following the guides above.

***​

Contents​

Overview

Downloads

Buttons

Unlock Bootloader

Rooting

How to use Odin

***​

Overview​

To root your device you need to first install the TWRP recovery. [MENTION=903232]Magendanz[/MENTION] includes TWRP in his ROMs, so you have two options, TWRP without custom ROM, or TWRP with custom ROM.

To be able to install a ROM or recovery you first need to unlock your bootloader.

WARNING - take note of the kernel version of the custom ROM or TWRP you intend to use, e.g. T510XXU2ASI4. Newer bootloader releases will sometimes prevent downgrading, so if you flash a firmware/ROM/TWRP with a later kernel version you may not be able to flash your desired custom ROM without problems, or flashing an older version than you are currently running may trigger anti-rollback mechanisms. Magendanz suggests matching the version exactly.

There are then two paths:

Original ROM:

Read the TWRP instructions

Download any zip you plan to flash (install) from TWRP (e.g. Multi-disable and Magisk) and save to your sdcard. Internal memory will be wiped (formatted) as a necessary step in installing TWRP (if you follow the instructions correctly). Note that the folder /sdcard is part of the devices internal memory, your actual sdcard data can be found in something like /storage/ABCD-1234 in Android, or external_sd in TWRP.

Unlock Bootloader - Click to see original post:

Disclaimer: your tablet warranty will void. Proceed with your own risk

Warning: your personal data, except on external SD card or USB drive, will be wiped during the process!

Prerequisite:

Host PC installed Samsung Smart Switch

USB C cable

Your tablet battery should be 70% or higher and you have done data backup

OEM Unlock enabled

1. About tablet

2. Software version

3. Hit Build Number few times

4. Enable USB Debugging

5. Allow your host computer

6. If you don't see OEM Unlocking, wait for 7 days or do the following trick

https://www.xda-developers.com/fix-m...galaxy-note-8/

Are you ready? Let's do it.

1. Turn your tablet off and disconnect USB cable

2. Press and hold both volume up and down buttons and connect to host computer

3. You should see factory reset screen, but this time you should see one more option. Press and hold volume up to unlock the bootloader.

4. If you see a warning screen on boot, the bootloader is unlocked.

Install TWRP recovery .tar.md5 file via Odin by following the TWRP instructions.

Click to see instructions from the TWRP OP -

From OEM stock firmware:

Unlock bootloader

Hold Vol Up & Vol Down buttons during restart to enter Download mode

Install TWRP to AP with Odin

Hold Power & Vol Up buttons during restart to enter TWRP recovery

Install latest Multidisabler from TWRP

Wipe->Format Data

Reboot to system

From existing TWRP install: (No need for data wipe.)

Hold Power & Vol Up during restart to enter TWRP recovery

Tap Install, select your update (.zip) file, and then swipe to install

Reboot to system

[Optional] Install Magisk to get root - see Rooting section below

Don't forget to install Multi-disabler

before

doing Format Data! (as described in the guide) - In TWRP tap Install then select the Multi-disabler zip file.

Custom ROM [Allow several hours for the custom ROM download]:

Read the custom ROM instructions: Nexus Stock / LineageOS 16.0

Download any zip you plan to flash (install) from TWRP (e.g. Magisk) and save to your sdcard. Internal memory will be wiped as a necessary step in installing TWRP (if you follow the instructions correctly). Note that the folder /sdcard is part of the devices internal memory, your actual sdcard data can be found in something like /storage/ABCD-1234 in Android, or external_sd in TWRP.

Unlock Bootloader - Click to see original post:

Disclaimer: your tablet warranty will void. Proceed with your own risk

Warning: your personal data, except on external SD card or USB drive, will be wiped during the process!

Prerequisite:

Host PC installed Samsung Smart Switch

USB C cable

Your tablet battery should be 70% or higher and you have done data backup

OEM Unlock enabled

1. About tablet

2. Software version

3. Hit Build Number few times

4. Enable USB Debugging

5. Allow your host computer

6. If you don't see OEM Unlocking, wait for 7 days or do the following trick

https://www.xda-developers.com/fix-m...galaxy-note-8/

Are you ready? Let's do it.

1. Turn your tablet off and disconnect USB cable

2. Press and hold both volume up and down buttons and connect to host computer

3. You should see factory reset screen, but this time you should see one more option. Press and hold volume up to unlock the bootloader.

4. If you see a warning screen on boot, the bootloader is unlocked.

Install custom ROM .tar.md5 file (which includes TWRP) via Odin, by following the custom ROM instructions.

Click for instructions from OP for Nexus Stock -

Unlock bootloader

Hold Vol Up & Vol Down buttons during restart to enter Download mode

Install custom ROM tarball (.tar.md5 file) to AP with Odin

When TWRP launches, wipe data if installing for first time. (Not necessary for incremental upgrades.)

Reboot to system

Click for instructions from OP for LineageOS 16.0 -

Unlock bootloader

Hold Vol Up & Vol Down buttons during restart to enter Download mode

Install custom ROM to AP with Odin

When TWRP launches, wipe data if installing for first time. (Not necessary for incremental upgrades.)

Reboot to system

Note that "wipe data" means Wipe -> Format Data

[Optional] Install Magisk to get root - see Rooting section below

Dirty flash: If you had installed the custom ROM previously and are now updating to a newer version then all you need to do is use Odin to flash the latest tar.md5 file. It will enter TWRP after the flash, no need to Format Data, just reboot to system. Alternatively if the ROM developer provides a flashable zip, you can update with TWRP.

Some users have reported getting stuck on the boot animation after a dirty flash, I don't know if that still happens with the latest versions of [MENTION=903232]Magendanz[/MENTION]'s ROMs. If it does the solution is to boot into recovery and flash Multi-disabler.

For TWRP versions before v3.3.1-5 you MUST format the encrypted data partition after flashing TWRP or TWRP will hang on the splash screen. For later versions of TWRP you should format the encrypted data partition after flashing TWRP so that TWRP can access the data partition.

You can use TWRP to flash zip files, e.g. to install newer versions of TWRP itself, or custom ROM zips, as follows:

1. Download the zip file

2. Boot into Recovery

3. Install -> Select the TWRP zip file

4. Reboot to System

You *cannot* use TWRP to flash tar.md5 files, and you must use Odin at least once to get TWRP installed in the first place.

***​

Downloads​

You may not need ALL of these downloads, this is just a handy list of some of the downloads mentioned in the guides

Samsung Smart Switch (for USB drivers)

Magisk - Download Latest Stable zip file to flash in TWRP (see Rooting below) and Latest Magisk Manager to install as an app

Odin

Multi-disabler (required by TWRP only tar.md5)

Firmwares SM-T510 SM-T515 - allow several hours, at least, for the firmware downloads to complete

WARNING - take note of the kernel version of the custom ROM you intend to use, e.g. T510XXU2ASI4 and your current version (Settings | About tablet). Newer bootloader releases will sometimes prevent downgrading, so if you flash a firmware with a later kernel version you may not be able to flash your desired custom ROM without problems, or flashing an older version than you are currently running may trigger anti-rollback mechanisms. Magendanz suggests matching the version exactly.

***​

Buttons​

Power On: Hold the Power button for 3 seconds

Boot to Recovery (Before unlocking bootloader) Power On and Press and hold Power and Volume Up until you see Recovery running.

Boot to Recovery (After unlocking bootloader) Power On and then press Power and Volume Up as soon as you see the unlocked bootloader warning. No need to hold.

Boot to Download: Press and hold Volume Up and Volume Down and connect to computer with USB cable.

***​

Unlock Bootloader​

Read the Unlock Bootloader Guide FIRST​

Click to see Unlock Bootloader original post...

Disclaimer: your tablet warranty will void. Proceed with your own risk

Warning: your personal data, except on external SD card or USB drive, will be wiped during the process!

Prerequisite:

Host PC installed Samsung Smart Switch

USB C cable

Your tablet battery should be 70% or higher and you have done data backup

OEM Unlock enabled

1. About tablet

2. Software version

3. Hit Build Number few times

4. Enable USB Debugging

5. Allow your host computer

6. If you don't see OEM Unlocking, wait for 7 days or do the following trick

https://www.xda-developers.com/fix-m...galaxy-note-8/

Are you ready? Let's do it.

1. Turn your tablet off and disconnect USB cable

2. Press and hold both volume up and down buttons and connect to host computer

3. You should see factory reset screen, but this time you should see one more option. Press and hold volume up to unlock the bootloader.

4. If you see a warning screen on boot, the bootloader is unlocked.

After unlocking the bootloader every time you turn the device on a warning about the bootloader being unlocked will appear for ten seconds, unless you dismiss it by pressing the power button.

If you are holding the Power button and Volume Up to boot into recovery this warning screen will flash on and off briefly, at which point you can stop holding down the buttons. Recovery will start a few seconds later.

***​

Rooting​

Root can be achieved by flashing Magisk in TWRP (you also need to install the Magisk Manager app). From Magisk 19.3 onwards there is no longer a need to use Magisk Manager to patch a tar.md5 file or anything like that.

You can even install Magisk the first time TWRP runs after flashing one of [MENTION=903232]Magendanz[/MENTION]'s tar.md5 files in Odin.

To do so follow [MENTION=903232]Magendanz[/MENTION]'s guide up to the point where you have Factory Reset/Wiped Data in TWRP then:

1. Reboot to Recovery

2. Install -> Select the Magisk zip file

3. Reboot to System

4. Install Magisk Manager

Otherwise you can start by installing the Magisk Manager app at any time.

Note: You will need to re-install Magisk after a TWRP update.

***​

How to use Odin​

Odin is a Windows tool for firmware flashing on Samsung devices via USB. Odin can be used to flash firmware, kernels, recoveries or ROMs to your device.

* Firmware zip (or rar) files need to be extracted and then install via Odin. Flashable zip files (e.g. new versions of TWRP or custom ROMs) can only be flashed from TWRP, not Odin, though you need to flash a TWRP tar.md5 file using Odin in the first place *

Preparing the device

Charge the device to at least 80%.

Bootloader unlocked

In developer options, turn USB debugging on. Click on Build number in Settings several times until you see the toast notification "You are now a developer". Go to Developer Options and turn on the USB debugging option.

- In the stock ROM Build number can be found here: Settings | About Tablet | Software Information and the "Developer Options" menu item appears below About Tablet in the main Settings screen.

- The locations may be different in custom ROMs. In the Nexus based ROM the locations are Settings | About phone for Build number, and System | Advanced for Developer options

Turn off the phone, hold down the Volumn Up and Volume Down buttons and connect the device to the computer with a USB cable (preferably the cable that came with the device). A warning will appear saying "A custom OS can cause critical problems in phone and installed applications".

Press the Volume Up button briefly to continue.

The device is now in Download mode.

Install Odin version 3.13.3.

When you run it a dialog will pop up in English and Chinese. Click OK.

The Odin window looks like this:

View attachment 4853507

Above ID:COM on the left is the progress bar, below ID:COM is the connection indicator which changes colour (and shows the COM id) when your device is connected in Download mode.

Below that is the "Log" tab which gives verbose output showing what's happening. Normally you will not need to go near the Option or Pit tabs.

There are four buttons in the middle of the screen corresponding to the types of file that you can flash: BL (boot loader), AP (Application Processor, PDA), CP (Core Processor, phone/modem), CSC (Consumer Software Customization)

Depending on what you are flashing you will need to load one or more files. To load each file type click on the corresponding button and select the file to be flashed.

Odin will show the following in the "Log" while the file is being processed:

<OSM> Enter CS for MD5
<OSM> Check MD5... Do not unplug the cable...
<OSM> Please wait...

For AP_ files this can take some time, during which the button will remain greyed out. When the file has loaded the "Log" will say:

<OSM> Checking MD5 finished Successfully...
<OSM> Leaving CS...

... the button will be enabled again, the text field beside the button will be filled with the fullpath of the selected file, and the checkbox next to the button ticked.

[MENTION=903232]Magendanz[/MENTION]'s TWRP and ROM files are both single files flashed to AP, so just click the AP button and the select the tar.md5 file.

If you are flashing firmware ( e.g. https://samfrew.com/model/SM-T510/ ) unzip the download into separate files and load each with the correspong button. The filenames begin with BL_..., AL_... etc so you'll know which is which.

There will be both a CSC_ and HOME_CSC_ file. You could flash HOME_CSC_ to keep your device's settings and data but normally you should use CSC_ for a clean install. If you have an SM-T515 then you'll have a CP_ file too, but if you have a SM-T510 then your firmware will not have a CP_ file because that's for the phone (SM-T510 is wifi only), so just leave CP alone, only load BL, AP and CSC.

Verify that your device is connected in download mode. The box below ID:COM should show the COM id of the connected device and there should be a line in the "log" saying something like <ID:0/008> Added!!

Click Start to flash the selected files. DO NOT UNPLUG THE CABLE UNTIL THE PROCESS IS COMPLETE. You can follow the progress in Odin and on the Download screen on your device. To flash a ROM or firmware will take several minutes.

If you are flashing one of [MENTION=903232]Magendanz[/MENTION]'s tar.md5 files then your device will reboot into TWRP once the install is complete. At that point continue following [MENTION=903232]Magendanz[/MENTION]'s guide.

Note: You will need to turn on USB debugging again after flashing firmware, or a clean install of a ROM, before you can use Odin to flash again. Also check that OEM unlock is still turned on.