After reading the text, NOW I found out what I need to do

What Glitch do I need to use?

Good map, indeed unintuitive because the hint to the next stage is inconspicuous and we have to know a glitch of the game, but all sections are possible. Good map those who want a little of a challenge.

(Sorry, for my english)

It is possible, although extremely unintuitive. The exit door will not open until all of the indicators are x. Once you make it out of the vents you can portal bump along the window to escape. In the next cell over you meet your companion cube friend and must escape through the secret gap in the roof. The companion cube must activate the button to reveal the other button in the final cell. The third cell has a secret passage to the second room which allows you to sneak your cube in onto the floor button, opening the door. The final objective is to deactivate the power cell holding the door closed. Deactivate the lasers and take out the power cell, careful not to drop it, and make it back to the exit door. Store the power cell for now, so you can retrieve your companion friend and beat the level.
I'm deeply sorry to anyone who spent more than half an hour on this.

im stuck in the vent section. is this possible to complete?

I've been here for hours and I can't get passed the second stage
is it even possible?