Autopsy result said there was no trace of drugs in her system.
Where are her clothes? (she was found naked and her clothes were not found)
Who closed the lid of the tank AFTER she got inside?
Why wasn't the elevator door closing, and why did it close right after she left?
Why, when the police with dogs searched the rooftop weeks prior to her body being found in the tank, didn?t they find any trace of her being there? No scent, nothing.

She appeared relaxed when she entered the elevator. Perhaps she clicked on different buttons to explore the place? She pressed them in a playful manner imo. (based on her blog she seems to be an art buff and maybe she checked-in the hotel for the classic/artsy/appeal or maybe of the history itself - thinking nothing bad would happen to her)
2nd time she pressed all the buttons she appeared to be panicking.

Her hand gestures seemed to be of disbelief (hands on head), stress (bending fingers), and waving her arms seemed like she was trying to trigger motion detector in the elevator door (if the elevator has it) or checking out why it's not closing (if there's some sort of hindrance/blockage) - trying to make sense of it all. Gives up, and tries a different route.

talking: maybe she was talking to herself- we do that from time to time. In her case maybe it went like this: "wtf? why is the elevator door not closing... what's happening?" and yes perhaps she went paranoid triggered by the circumstance she was in. Ik I would be esp being alone and all.

None in the video made me think she's mentally ill --- to commit suicide. I think there's something more to this, too many questions unanswered.