Why is the biochemical hotel crossing the line of fire stuck underground?

Squat in the corner, then aim at the corner and slide in.

Sliding step: when squatting, press W, En S plus D or A to change the knife and aim at the opposite side. The sliding distance should not be too large. Jump sideways, hold down shift (static step), and quickly cycle w+s. When you find yourself falling in a little bit, wait for 2 seconds, press w+ to squat down, and you will go in.