I have a Samsung Galaxy A20 and I was attempting to unlock the bootloader and also install TWRP. While the bootloader was unlocked successfully, while doing the TWRP part I had to use Odin and used an online tutorial to see how to do it. I ended up putting it in Odin's AP section and flashing it....
and that was the last time I saw my A20 working normally...
Now I can't switch it off (unless discharged) and it stays on all the time.
What if I try to switch it off? When switching off is attempted, it shows me the standard Samsung boot-up screen but with a yellow triangular warning sign and red text at the bottom saying "This phone is not running Samsung's official software. You may have problems with features or security, and you won't be able to install security updates." And then I'm back to the download mode screen.
I cannot go to the recovery/bootloader. I have tried pressing the buttons on the phone all at once (i.e. power; volume buttons) with no results.
In the Download Mode screen it shows:
In the middle of the screen: A big download logo with the text "Downloading..." below it and below that, "Do not turn of target". After some blank space below it there is the text "Volume Down Key + Power Key for more than 7 secs : Cancel (restart phone)".
On the top left: There is text in three lines and has a really small size.
Note: A ? indicates incomprehensible letters due to screen layout and a @ indicates unknown number of letters that cannot be viewed there
?ecovery: Error validating footer. (@)
VBMETA A205WLS2ASG1, 25128537R
By the way the device region is either VMC, VTR or XAC.