I will try again and wait an hour of just seeing the Samsung Galaxy S5 Neo screen.
To me, the build might be a potential avenue to pursue.
TWRP old and new seemed to work (able to reboot, able to issue adb sideload command, able to install zip on sdcard). I could also try installing with Odin.
Will keep this post updated when I have time to test those things.
Thanks @greg.weber for your ideas.