i have a similar situation going on right now.
difference is: i did not update anything, i have been using the most recent v3 for the standalone and the plug the whole time.
unfortunately, c4d craashed while working and i had to force quit c4d via task-manager.
murphey's law or whatever wants it, that in that moment my internet connection was offline for a few minutes.
next time i tried to start c4d, octane gave me the pop-up that you see above (wrong username or password).
now i seem not to be able to log-in. no username/password combination works.
to be honest... it's a bit confusing... forum, livedb, account, standalone, plugin, everything's a bit splattered all over the place.
but i tried every possible combination of names and figures i possibly could find concerning octane.
of course i also tried those:

but still... "invalid user or password".
i tried it via starting the standalone and typing in in that pop-up. as well as i tried via launching c4d and typing in in the pop-up that appears there.
as you can see in the screenshot, it says "deactivated". after my problem occured, i read in the forums and i found as an alternatve emergency solution, if the software could not release the license due to internet connection break-down or so, that one can manually release via web-page. so tried that, now it says "deactivated". before that it said "unlock", i had to click it, so now it says "deactivated" hoping that now i would succeed, but still no luck.
i also read in the forums, that deleting the file "otoy_credentials" from the ...roaming/octanerender place could be a solution. i can't find a file named like that. i only do find "otoy_credentials.backup" though. i deleted that one but again and still: no luck.
now i am in the situation that i am not able to use the software, neither in standalone (which i've never used anyway really) nor in c4d.
i am approaching the end of a production process, in the middle of rendering out the final frames with higher sample rates and in need for this weekend as rendering time for the frames to be finished by monday morning.
and now this!
please, pretty please, with sugar on top: i need help to get this software running.
this situation is everything but funny.