So, it’s a cool idea that it’s a “closed system” and doesn’t need any refilling. However, mine was mishandled by movers. This includes storing it on its side, and possibly even upside down though I have no proof of that. A very significant amount of the oil has leaked out.
I see no simple way to check or refill the reservoir.
I’m pretty sure it’s mineral oil, so while it’s made a mess it’s not going to corrode anything or cause a short circuit in the electronics. I use a liquid CPU cooler in my workstation and it’s plumbed with the same stuff for the same reason - leaks are at worst a mess to clean up.
The reservoir is under the left side panel. On my GF at least, it’s a white plastic bottle with a screw cap that can almost certainly be removed to add more oil.
So I would say your odds of recovering from this are good. But before you start taking things apart, you should wait for Customer Support to chime in…
Mineral oil acts as a good thermal conductor and is nonreactive electrically. There are some folks who will immerse their PC in it to provide cooling - it’s something the hardcore gamers & crypto currency miners do.