I believe Elisa died from accidental death from her manic episode however she might have been killed by a hotel employee. It makes more sense on how the lock on the top of the tank was already unlocked. The hotel says the alarm to the door at the top of the hotel didn’t ring when Elisa got there, and an employee could have lifted the top of the lid. “An alarm will sound if someone attempts to open the door to the roof if it is not deactivated first, something that typically only hotel employees would be able to do” (Rylah). The hotel employee could have manipulated the alarm, so it wouldn’t ring and unlocked the tank with the hotel keys.

The employee likely could have killed Elisa Lam considering the alarm and hatch situation on the tank. It looks like some had to do have done it.