I think I fried my iPod with the wrong power source.

I plugged my iPod into my inMotion speakers, but it turns out I had the wrong power adapter connecting the speakers to the wall. The speakers say DC IN 5V, and the adapter says 9V 1.11a.

I didn't know it was the wrong adapter until I inserted my iPod and the speakers (still off) started making a buzzing sound. The iPod then displayed: Connect to iTunes to restore. When I felt the upper back case, it was hot, and now it won't turn on at all. I've tried connecting to iTunes (nothing happened), reseting (nothing) and trying another power source (nothing).

What part of my iPod do I need to replace?