SAMSUNG a10s boot loop after TWRP flash

Question

I have bought a SAMSUNG A10s phone and tried to install TWRP according to this instruction. I was able to unlock the bootloader and enter the 'Downloading' mode.

I disabled time sycro and automatic updaten, set the time to a few weeks ago and connected the wifi in order to overcome this issue.

I used a Debian computer and the Heimdall tool to flash this TWRP image into the recovery partition (which replaced the existing recovery.img, I took no backup - daft, I know).

Caused by the unlocked bootloader I got a warning with every startup. The usual key-combination for the bootloader menu did not work. So, after a few boot procedures, I tried the offered option to lock the bootloader and perform a factory reset.

Unfortunately, this brought me to bootloop. I was only able to enter the 'Downloading'-mode again. Now, the bootloader is locked again but the images are invalid. I get this error message:

<!>
Partition recovery
Reason recovery: Eroor verifying vbmeta image: invalid vbmetaheader
SAMSUNG recovery, A107FXXU7BTL1, 36415554R
SAMSUNG vbmeta, A107FXXU7BTL1, 36415554R

Quitting this 'Downloading' mode brings me back to the loop which reaches the SAMSUNG logo before it boots angain.

Can anyone explain this situation? Has anyone an idea for a solution? Using Heimdall, I can still read the PIT. So, maybe I can also flash any images. I am very glad for help!

I am already downloading the corresponding firmware from sammobile. — peng, Feb 22 '21 at 20:48
Does this answer your question? How to use ODIN with more than a dozen of mbn, bin, img, ext4 files? — alecxs, Feb 22 '21 at 21:18
after unlocking bootloader (and necessary factory reset) one must connect wifi and oem unlock again to disable vaultkeeper — alecxs, Feb 22 '21 at 21:20
@alecxs thanks for your comment. Indeed, I had to disable automatic updates, to set the time longer than 7 days ago and to connect the wifi. This was before I was able to flash anything. — peng, Feb 22 '21 at 21:29
be aware bootloader is not downgradable, therefore i recommend to flash U7 as higher bootloader level may lead in non-unlockable bootloader — alecxs, Feb 22 '21 at 21:30
@alecxs - I can see the U7 in the error message as a part of the checked image, isn't it? But what does it mean that here, it refers to U7? — peng, Feb 22 '21 at 21:33
yes that is your current bootloader level i am refering to. i don't know which stock ROM you have downloaded but there might be a risk after flashing latest available version your bootloader is locked down entirely and the 7 days trick won't work any longer. therefore flash oldest possible stock ROM (which is U7 already in your case) https://android.stackexchange.com/questions/234025/how-we-can-know-from-download-mode-screen-if-device-galaxy-tab-s6-is-factory-n#comment310253_234025 — alecxs, Feb 22 '21 at 21:36
@alecxs Unfortunately, I know the message "only official released binaries are allowed to be flashed" you quoted yesterday. This was shown in the Downloading Mode after failing to access the TWRP menu. So, can you recommend any strategy for solving this issue without causing remaining damage? — peng, Feb 22 '21 at 21:41
but vaultkeeper is a different story - basically just don't forget to unlock bootloader twice before actually flashing custom binary — alecxs, Feb 22 '21 at 21:42
@alecxs I am not sure. I missed the unlock field in the developer menu, so I followed this recipe. — peng, Feb 22 '21 at 22:01
@alecxs - I am still in the same situation. Right now, I installed JOdin. The phone is connected but I cannot access the PIT. Furthermore, I am not sure about the firmware offered here .. it is just 32 MB. Do you have any ideas? — peng, Jul 03 '21 at 11:56
both download links provided work (2.8GB) you probably clicked the wrong link for boot.img only. unzip the download (3.2GB) and flash the four tar.md5 files according to it's prefix — alecxs, Jul 04 '21 at 08:21

SAMSUNG a10s boot loop after TWRP flash

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