Okay, I've ordered another AC adapter for the piano online. It should arrive tomorrow. I just cannot imagine that something terrible has happened to the piano, because it just WON'T TURN ON. Like, it gets no power at all, no matter what outlet the AC adapter is plugged into. So I think that the problem is the adapter, because I know that they piano itself was working great when I bought it, and that nothing has really happened to it since that could have completely fried it.

Tomorrow we'll find out if I'm right.

Wish me luck.