Heimdall v1.4.2
Copyright (c) 2010-2017 Benjamin Dobell, Glass Echidna
http://www.glassechidna.com.au/
This software is provided free of charge. Copying and redistribution is
encouraged.
If you appreciate this software and you would like to support future
development please consider donating:
http://www.glassechidna.com.au/donate/
Initialising connection...
Detecting device...
Claiming interface...
Setting up interface...
Initialising protocol...
Protocol initialisation successful.
Beginning session...
Some devices may take up to 2 minutes to respond.
Please be patient!
Session begun.
Downloading device's PIT file...
PIT file download successful.
Uploading RECOVERY
100%
RECOVERY upload successful
Ending session...
ERROR: Failed to receive session end confirmation!
Releasing device interface...
On a smartphone
*Only official released binaries are allowed to be flashed*
this is due to a samsung protect feature, well known by @aibd ( Know your hardware - Samsung )
please share a photo of your phone’s download mode screen
As predicted by @piero your phone is showing Prenormal. This is a conditional lock. Perhaps the solutions for S10 devices jumped out at you because they are more recent additions.
You might have use your skill and judgement to see if you can see which of the mentioned locks could have been applied by Samsung in your case.
