Need urgent help, possible drowned millipede

My roommate left me to take care of his millipede while he was away on a school trip. I had taken care of her before so when I noticed her water bowl was almost entirely empty, I gave her some more. I made sure it wasn’t quite enough to cover her body, and made sure to have one of the sticks in the tank so she could climb out if she fell in. I usually only check on her once a day (when I get home from work) since she’s more active at night, and when I checked on her today I noticed her sitting in the water bowl and panicked. I took her out and she wasn’t moving after I touched her. I’ve placed her back on the dirt for now to give her time in case she is still alive but I just don’t know if there is more I can do. Please help if you can! I’ll take any advice I can get. I already let him know she may have passed but I would love to be wrong.