What will happen If I don't login at all.

Any action other than giving me release?

Most likely the basic question they will ask is are you on leave if yes why u didn’t inform your peers if not can we know the reason, and you say your reason and they will tell its not the way it works blah blah blah and they will make a big fuss about it. Better talk to manager directly else find a loophole to fix escape. Don’t give them a chance to question you.