It's very sad but there's not the slightest bit of evidence to suggest anything spooky or unusual, except for the edited footage (the unedited footage doesn't look "spooky" or whatever).
She was seriously mentally ill (had documented her struggles with her mental illness in her blog) and had recently stopped taking some of her medication. She had been prescribed both anti-depressants and anti-psychotics but stopped taking the latter only. It's actually more dangerous for a person with a history of mania and psychosis to take anti-depressants alone than to take nothing as ADs are known to have an increased risk of mania in people with BPD.
Nobody saw Elisa with anyone and there are no suspects or reason to suspect anyone.
Elisa was known for liking to climb onto rooftops and enjoyed rooftop photography, and it's on the record that the door to the roof was unlocked and open, so it's not surprising or even unlikely for her to go out onto the roof. Even after her body was discovered the roof (which was a crime scene!!) was still unlocked and not alarmed.
The water tank was very easily accessible via the fire escape, and the lid to the tank was hinged meaning it would have been very easy to lift. (Internet Detective-types and YouTubers have visited the hotel and filmed themselves lifting the lid - it is not heavy and would not have been difficult for Elisa to lift alone.)
Stories differ as to whether the lid was open or closed when she was found, but the lid could easily have been closed either by the wind, or simply by the force of gravity (or she may likely have not opened the lid fully, but just opened it a crack to slip inside). Of course that doesn't apply if, as the maintenance man insists, the lid was open when she was found.