Here is my theory about what happened.
Elisa lam went into an elevator. She pressed random buttons because maybe she forgot what floor her room was. The elevator door started to close but it stopped. You can see that in the last video of her. It happened because someone or something was pressing the elevator button the whole time for the door to stay open. She started to peek to see if anyone was pressing the elevator buttons. Then she saw someone or something that terrified her. She decided to stay in the elevator and keep pressing random floor buttons but the creature kept pressing the elevator button for the door to stay open. Elisa Lam started to panic. She looked around for help. She tried not to angry the thing that was there. Later in the video you can see her doing sign language for the creature to understand her. Because she wanted it to leave her alone but she didn't succeed. Later when she went to take the stairs the creature's chance had come and put her in the water tank and then see d*ed. That's my theory.