I don't really understand how she could close the lid or how it could close on its own. Hinges or no hinges.
The only explanation I can think of that goes along with this being an accident and no one else is involved in the slightest is the lid mysteriously being off the tank is a frequent occurance at this hotel. So, sometime later than when she drowned, but before she was found, someone noticed the lid off and put it back on... which is scary because it suggests people randomly taking the lids off is just taken for granted.
I have seen the suggestion that the lid is hinged and the wind blew it closed. I just don't know if the lid is situated on the tank in the right position for that, but I have only see photos. Also, it seems the tank manufacturer, even back in the day, would make it where a gust of wind wouldn't cost a worker his life. I read tank safety standards actually began long before the hotel was constructed. So even if these tanks have been there since 1927 (which I hope they haven't), they should at least have something to prevent this. But, maybe they do and that feature has to be purposely engaged. Still, this doesn't account for stiffness of the supposed hinges and we don't know how much the lid weighs or how likely it closed by itself. However, this is the second most likely explanation for the lid being closed.
Then I read someone saying maybe she balanced the lid on her fingertips and pulled it closed in this manner. But, since this was proposed before the 'accidental drowning' was announced by officials the person may not have meant she did this by accident. But, even if one supposes she thought the lid was something else and didn't realize she was trapping herself (this will only be the case if she was misperceiving her surroundings), is this even possible? Meaning could the tank even be closed in a gradual manner.
Finally, there's this.. maybe it wasn't closed. Maybe during the dog search, the police didn't check the tanks individually. They just saw the lids on the other tanks and couldn't see this tank clearly, but assumed it would be the same.
Then, the maintenance man on the 14th might have been the one to replace the lid (if it was off). Although I question whether it really could've been off that long because sunlight would have rushed certain things along... Nonetheless, I doubt the hotel wants much talk from their employees about these lids because they weren't up to code. The tanks were supposed to have locks on them. ChelleBelle went some time after Elisa was discovered, and also after the Chinese investigator, and she found the lids are FINALLY locked. Same lids, but with padlocks added (she posted photos somewhere on here).
I think these stupid lids are important. Elisa's tank lid does look like it was exposed to the elements for a while. Meanwhile, someone (maybe just the media in their helicopter) got a photo of another one of the tank with its lid off and that lid didn't look like it had been exposed to the elements. The edges were still clean and silvery gray.
So, it is not too difficult to imagine that someone carelessly left the lid off at some point for Elisa's tank. Possibly before she encountered it, for all I know.
Sorry to ramble on.. these lids just bug me. They're important.