[Miscellaneous Android Development] IamTheBRAVE:
Hello and welcome

I'm sure a lot of galaxy A20 owners like me are experimenting with all the new improved toys :D brought to us by android 10 development lately and also by the recent breakthroughs made by Master Guinea Pig Phizzwizz :p and his trusted followers.

All right, let's begin. First things first: you know that any modification you make on your phone is your responsibility alone. You are the only one able to assess how much risk you're willing to take whenever you flash your phone. Anything can go wrong at some point and you should be able to rescue your phone provided the damage is reversible.

What i mean is if you hard brick your phone there is nothing i can do for you. Other than that, if you end up with a soft brick or bootloop, this tutorial is for you.

My device variant is 205F, and this tutorial will be oriented towards that. Apparently, all procedures for it are also working for the 205YN (still needs full confimation) others like 205G or 205U have different procedures, but restoring your phone to stock should work on all variants, because it's the standard way of doing it in other android devices.

I assume you have the necessary tools to work with: the firmware files of your variant, Odin's latest version (always make sure to disable auto-reboot in options, it's better to do it manually), the modded boot.tar for root, and the TWRP file provided by Afaneh in the 'TWRP recovery project' thread (if you wanna have another try at rooting and installing a custom recovery on your device)

Reboot your phone into download mode (plug cable to PC then vol+/vol-)

Launch Odin with admin rights and make sure you get a "pass". Add the firmware 4files (AP,BL, CP, and CSC/HOME_CSC) to the appropriate slots and flash (i was able to restore my phone with AP alone, but there may be some things not working right that are related to the other files). It Should take 5 to 10 minutes.

Unplug your phone and reboot. You should land at the "Welcome, Setup your phone" screen.

## You should stop here, and ask yourself: do I want to risk breaking my phone again or do I want go further?##

If you decide to go on, complete the setup by skipping all menus you can (always make sure you enable dev options and USB debugging and unlock bootloader if they are disabled, or reboot after any flash will result in "unable to load the system" in bootloader or a bootloop) then reboot to download mode then in Odin, flash the magisk modified boot.tar (you get it following the instructions in the 'Rooting your galaxy A20' thread).

Exit download mode (long press vol-and power until you get cramps) then reboot to stock recovery this time (vol+/power) and factory reset the phone.

Finish setup then install flashify and choose your TWRP recovery img. Your phone will reboot and go to custom recovery. Be careful what you do here, you may break your phone again!

##again you can stop here or go further and free yourself from Samsung Jail##

Reboot to TWRP and do a factory reset from there then flash the GSI alone. Reboot and you should get to the android logo. Finish setup and you're done. If you get stuck at the logo, there are a couple of zip files you can flash one by one and see if it helps. You can get them from here:

https://www.xda-developers.com/flash-generic-system-image-project-treble-device/

Make sure you read the article thoroughly and only flash what is necessary.

That's it. You should have a working GSI, enjoy!