Casio PT-10 is screwed

[iwillbeacircuitbender]

So, I got this from Goodwill Sunday
Powers up and sounds normal, but kinda glitchy
Half the keys don't work, so I tried replacing the batteries, did that, still works, same behavior. And the other thing is, when I press a key at the top of the keyboard it also plays and 2nd note right after. And sometimes on powerup, it blurts out a note
I'm thinking the key matrix is buggered
This keyboard is exactly the same as the VL-1, but no calculator or LCD display