The Mysterious Case of Elisa Lam

What has happened here? A young, perfectly healthy, attractive, qt-asian-3.14 found oddly enough with no signs of struggle drowned within a hotel's water tank.

Video of it

News report

The story goes as follows:

At first, Elisa enters the elevator and apparently presses all of its buttons. She then waits for something to happen but, for some reason, the elevator door doesn’t shut. She starts to look around, as if she is expecting (or hiding from) someone. At 1:57, her arms and hands start moving in a very strange matter (almost not human) as she appears to be talking to someone, something … or nothing at all. She then walks away. The elevator door then shuts and appears to start working again.

Seeing the surveillance footage, most people would conclude that she was under the influence of drugs. However, Elisa did not have a history of drug use and her autopsy concluded that no drugs were involved. When one looks at the context and the circumstances of this death, things become even more mysterious

As the reporter states in the video, the rooftop area is protected by an alarm system and the water tank is difficult to reach. How did Elisa reach that area? Also, how did she close the water tank lid?