Sister in law lost controller and returned it after a year, checked batteries and they were fully rusted and this is how the inside looks; is it safe to use?

Slight rant within the explanation btw. Not quite sister in law, the sister of my partner whom I plan to marry someday. I lived with their family until recently. For context her room is disgusting which is how I imagine this happened. She swore she left it in the living room, again and again, but it was never there. She unoficially left about 10 months ago and officially moved 5 months ago, I let her borrow the controller a year ago. Her room was so disgusting and filthy we avoided it (dog constantly pissed in there and was not taken care of so it was unsafe). This last week she was back in town and found it in her room and used the excuse "someone must have seen it in the living room and put it back in my room" (everyone knew the black controller was mine and hers was the white, though). So I'm not shocked it got ruined but am angry. Any chance this is still safe to use or no?