Last night I got a popup saying there was a critical update that needed to be done, I updated and after that origin was constantly in Offline Mode, when clicking Go Online, nothing was happening.

I closed origin(exited directly) after firing it back up it took me 1-2 minutes before the Login form appeared, till then it was a spinning circle. I was greeted with a "Online login unavailable" message above the login form, after logging in I was still in Offline Mode and cannot play Crysis 3.

I then uninstalled and re-installed Origin, hoping the error would be gone, it's still there but this time I could no longer login.

Odd.

Origin sometimes seems to refuse to connect... just give it a while and it'll be back to normal

It's been like that since last night, I slept for a good long while it's still like this.