Samsung A20 SM-A205W stuck on download mode 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 &quot;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.&quot; 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 &quot;Downloading...&quot; below it and below that, &quot;Do not turn of target&quot;. After some blank space below it there is the text &quot;Volume Down Key + Power Key for more than 7 secs : Cancel (restart phone)&quot;.
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. (@)
CUSTOM RECOVERY
VBMETA A205WLS2ASG1, 25128537R

By the way the device region is either VMC, VTR or XAC.
Thank you
It sounds like a soft-brick. 
To unbrick your device, download stock firmware for your device from sammobile.com and flash it using Odin. Make sure you download the right one for your region.

For more details: See this