[Samsung Galaxy A51 Guides, News, & Discussion] DerTopher:
Here is a quick how-to guide to flash LineageOS 19.0 to the A51​

Disclaimer: I am not the maintainer of any of the files I link to here. I just wanted to share my experience to make the process of Flashing los19 to the a51 easier for others.

Prerequisites:

1. Unlocked Bootloader

This step is crucial. You need to unlock the bootloader of the A51 before trying any of this. If not, you are likely to brick your device.​

1.1. Unlock developer mode by standard procedure: Settings > Info > Tab 7 times on build number​

1.2. Enable USB debugging in Developer Options​

1.3. Enable OEM unlocking in Developer Options -> To see OEM unlock option I needed to connect to my WIFI, then set the phone date manually to March 7th 2019. Only then the OEM unlock option became visible in Developer Options. Yes, this is super dumb and inconvenient...​

1.4 After triggering OEM unlock option shutdown your phone.​

1.5 Enter Download mode by: Pressing Volume+ and Volume - while at the same time plugging in the USB cable that is already in your PC.​

1.6. To finally unlock bootloader, you will see a green screen on which you need to press Vol + for some time. THIS WILL VOID YOUR WARRANTY. It will also erase all data on your phone!​

1.7 After reboot repeat steps 1.1. - 1.5. again. This time you can actually enter download mode by pressing Vol + shortly on the green screen.​

2. Flash Twrp

You can now flash TWRP via Odin. The TWRP img I used is here: https://www.mediafire.com/file/0h14t0263oujhna/TWRP-11-3.6.1-a51-20220321-1406-hotfix.tar/file. I flashed it as AP. Make sure to uncheck Auto reboot before flashing.​

When flashing is complete hold Vol - and Power until reboot.​

Immediately when rebooting hold Vol + and Power until Samsung logo appears, then let Power go but hold Vol + to enter TWRP.​

3. Actual Flashing:

3.1. Necessary Files:​

Make sure to load all files necessary to your SD before flashing:​

ChonDoe_Flasher, Disable_Dm_Verity, Multidisabler, LOS-Imagefile, Magisk(optional)​

​

As for the LOS Image I used this file here, which already includes gapps:​

lineage-19.0-20220211-UNOFFICIAL-treble_arm64_bgS-vndklite.img​

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If you don't want gapps pick an image that says "BvS" instead of "bgs"​

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3.2. You need to move your LOS-Image to the same folder as ChonDoe_Flasher and rename the file to "system.img"​

3.3 Flashing Sequence:

In TWRP Follow this sequence:

3.3.1. Wipe data, dalvik, cache​

3.3.2. flash disable_dm_verity​

3.3.3. flash multidisabler​

3.3.4. Wipe internal storage (Backup might be advisable, if you didn't format data anyways)​

3.3.5. reboot recovery​

3.3.6. flash chondone with lineage-19.0-20220211-UNOFFICIAL-treble_arm64_bgS-vndklite.img in the same folder renamed to system.mg​

3.3.7. Wipe data​

3.3.8. Reboot​

That should be it. First startup takes some time, your phone should boot to LOS 19.

4. Anger Management

If you softbrick your device you can try to go back to stock rom by accessing download mode and flashing it via Odin. Will take some fiddling around with the button combinations.

If you hardbrick your device don't hold me responsible and good luck to you!

Thanks to

Kyau Sana, Vadim Kupriyanov, Knoyan GTR-X and Sara Lins and other, from the telegram-group, who helped me figure out the process.