[Galaxy A3, A5, A7, A8, A9 Q&A, Help & Troubleshoot] Votum38:
Help! My phone is now stucked on a boot logo. I tried rooting and flashing via odin on Oreo, after then, it stucks on boot loop, on which I know how to fix, going back to stock rom works, but then signal is gone (boot loop wasn't expected, didn't managed to see bandbased version) I then, flashed this: https://xdaforums.com/showthread.php?t=2420881 through odin via AP, which is a wrong method on which I know I am stupid enough, right after then, OS won't boot up but stuck on boot logo, also tried using TWRP and Official Lineage OS 14.1 and the same thing happened, it starts to boot up, it rebooted after a few mins, then it goes back to TWRP.

HELP, I think the wrong method of flashing of this: https://xdaforums.com/showthread.php?t=2420881 file is the mistake, idk what did I messed up with it, it was supposed to be used for EFS restore app not flash through Odin, what should I do? Any OS just stucks on boot logo but download menu and recovery mode (official/twrp) is still there, also the phone is still viable to be flashed.. Please help.. I just got this phone not even 24 hours ago.. Lol, I know stupid me, that I didn't checked the file carefully, I learnt my lesson, criticize me or anything.. But please, help if you can.

I had not known that the Marshmallow, Nougat and Oreo was pretty harder to do things on, I'm quite new with this new OS release, I was pretty confident because I was doing this all over the years (I only know step by step, not really in-depth information). Way back, odin only requires AP, now it requires 4 columns on which I cannot reflash without unchecking the Bootloader.

P.S. Before boot loop starts to happen I tried rooting on Oreo, downloaded my own country region openline version(I am openline, yes) and also tried Lineage OS 14.1, Now, I am trying to download Russia(not my country) Stock Rom Oreo, it might be the case that it doesn't allow me to flash bootloader as this was the downgrade, and I skipped right through it. But I am worrying about the wrong flash file and after the download finishes, the same thing happens and I won't be able to get passed out of boot

EDIT: I've did everything and ODIN works for the flashing the whole columns including bootloader with russian full stock ROM, but its still stuck on boot logo, EFS not detected on recovery. I'm losing hope, this is not recoverable yeah?

Here's the error code on recovery mode:

#fail to open recovery_cause(No such file or directory)#

#Reboot Recovery Cause is [Unknown]#

No Suppport SINGLE-SKU

E:Failed to mount /efs (Invalid argument)

File-Based OTA

E:Failed to mount /efs (Invalid argument)

Supported API: 3

E:Failed to mount /efs (Invalid argument)

E:Failed to mount /efs (Invalid argument)

E:Failed to mount /efs (Invalid argument)

dm-verify verification failed...

E:Failed to mount /efs (Invalid argument)

E:Failed to mount /efs (Invalid argument)

E:Failed to mount /efs (Invalid argument)

E:Failed to mount /efs (Invalid argument)

E:Failed to mount /efs (Invalid argument)

E:Failed to mount /efs (Invalid argument)

... and so on.

E:failed to clear BCB message: failed to find /misc partition