in v5b1 I had no bootloader information with the /system routerboard print command. It was empty “” where it usually is “2.20” for example.
I uploaded v5b2 and it did not upgrade on reboot. Two attempts - the board did not even power up wihtout adapter unplug.
Then I clicked the button Downgrade - the board upgraded to v5b2 LOL LOL LOL.
Had packages missing - so the up/downgrade procesure was stupidified (this way was not intended by the developers probably).
So I uploaded the missing packages and now it seems working. I will send a supout and ask support whether I should downgrade , re-upgrade, reflash via serial or waht. Because so far it seems working but there were weird entries in the log. Like orphaned files etc. Sheise.
P.S. WAIT LONGER when you do these things. Maybe I did not wait long enough.