There's not much he can do with the comatose Rosa. Let's explore the place while we wait for her to wake up.
Hint 2
Going through the door brings you to a simple intersection. You can go right to hospital reception, across the hall to an empty padded cell, or left to a doctor's office and a storeroom. Try them all.
Hint 3
In the reception area, the only interesting thing is the window, which shows a rip in the sky that seems to be Madeline's work.
Hint 4
In the doctor's office, you'll find Dr. Quentin from the first game dictating his report on Rosa's condition. Alas! but not helpful.
Hint 5
In the storeroom, there's a notice on the wall to the right of the white lockers that's interesting.
Hint 6
Finally, go into the empty padded cell to find --
Hint 7
-- that it's not so empty after all. If you read the notice in the storeroom, you'll have a long conversation with this guy that explains everything --
Hint 8
-- and nothing. Forget the details; the important info is that Madeline is trying to destroy herself by ... destroying the rest of the city? Well, whatever.
Hint 9
There's nothing else Joey can do on his own. The only thing he can do is try talking to Rosa's unconscious body again. It might work this time; and besides, as he says, talking is all he's good for.
Hint 10
This automatically switches you back to Rosa in the void. Time to go, girl.