please don’t get me wrong, but from a distance, what I’m describing sounds a bit mysterious.
How many days and hours has the S9+ been blocked?
Normally, the blocked RMM status returns to normal within a certain time, e.g. within seven days (168 hours). After seven days (24 hours each) at the latest, the OEM unblocking option should be displayed again and the RMM status should be normal. So much for the theory. There are tricks to bypass this 7-day lock, but I recommend you wait and see first.
[???] Was your very first attempt to flash /e/OS with the /e/asy installer tool?
In any case, I would already try to flash the current stock Android 10 with security patch level 2021-03-01 with Odin v3.14.4. This will restore the device to its current factory state and fix any bugs. You should, of course, choose the right build for your region.