[Samsung Galaxy Tab A series Guides, News, & Discus] mingkee:
Warning:

Proceed with your own risk. I hold no responsibility if something goes wrong and you get killed.

Warranty void

KNOX tripped and some security feature won't be available

This guide based on [MENTION=4470081]topjohnwu[/MENTION] Magisk for Samsung. However, T510 is a bit different because it doesn't have Bixby button.

https://topjohnwu.github.io/Magisk/samsung

You need the latest Odin (I use 3.13). 3.12 or older won't work

***** NOTICE *****

Auto reboot must be disabled.

Download ROM matches your build number especially the last three characters. Unzip and only use AP and copy it to your tablet

Download ***special*** version Magisk Manager to your tablet and install it. "Install" Magisk using patch boot with AP file, and copy magisk_patched.tar to your host PC

https://raw.githubusercontent.com/topjohnwu/magisk_files/master/canary_builds/app-release.apk

Do not use normal Magisk to patch AP because it won't work

Bootloader Unlocked (read my guide)

Do not restore yet until this process is done.

STEPS:

1. Download your version of ROM. Make sure it matches your device Build Number

2. Unzip the ROM and copy AP to your tablet. Install Magisk Manager downloaded from link above. Normal Magisk Manager won't work.

3. Patch AP with Magisk Manager. The output file is "magisk_patched.tar". Copy the output file to your host computer.

4. Open Odin. Make sure Auto Reboot is disabled (unchecked)

5. Turn your tablet off. Press and hold Volume up and down buttons and connect your tablet to host computer. Press Volume up again to enter Download Mode.

6. Odin should show "Added". Locate your "magisk_patched.tar" and open as AP (it's AP after all). You don't have to flash others.

7. Wipe your tablet.

Disconnect your tablet.

Press and hold Power and Volume down.

As soon as the screen goes dark, immediately press and hold Power and Volume up until recovery screen appears.

Choose Factory Reset and press Power once, and confirm.

Reboot System Now

8. As soon as the screen turns dark, press and hold Power and Volume up buttons before screen shows bootloader warning. It will reboot again like brand new unit.

9. Do initial setup. Copy the Magisk Manager to your tablet and install if you don't see it

10. Setup internet connection and Magisk Manager will do some process, and it will reboot after it's done. You don't have to do button combo at this time.

11. Open Magisk Manager again to add other function including hide.

Your tablet should be rooted. However, here is something you should know.

Press Power button only: System with Magisk

[*]Press and hold Power and Volume up buttons before the screen shows bootloader warning and release: System with Magisk

Press and hold Power and Volume up buttons all the way: Stock recovery

That's it. Root is done.

***** IMPORTANT *****

If you want to do manual update, make sure you do steps 1-6 again. You don't have to wipe your tablet however.

Update: it appears "normal" Magisk (19.3) and Magisk Manager can simplify the entire rooting process.

Special instructions for Samsung is gone now.

Moreover, it appears normal boot can enter rooted system without button combo