We opened the two windows that could be opened but it didn't know how to get out. Our space is very high, we couldn't reach the bird and hush it out (no tall lightweight objects around). the bird was sitting on lamp chords like they were reeds sticking out of water.
Getting it out back through the door was out of question: we could have got it back into the corridor but the corridor has no windows that can be opened. If we got it out through the door through which it had entered, we should've first chased it first into the corridor, make sure it doesn't turn left towards the light, but down the stairs and then make it sure it doesn't fly towards the light coming in through the window in the stairs as it can not be opened either, but make sure it flies down the stairs, and then out of the front door. I'm pretty sure birds don't get the concept of "going down the stairs".
Luckily just as I had googled "How do birds see?", and seen this potentially helpful image
the bird flew out the open window.
