Return to the elevator immediately.
First, find the elevator door, then turn around and go down, then turn left. You will encounter a person blocking the way. Crouch in the grass on the right, go around and. go up the slope to the right. Fang walked to the third floor, squatted under the car, waited for the enemy to pass, then went upstairs, ran to the third floor, and entered the room on the left to start the generator. The final step is to start the engine and return via the original route.