Static noise through all audio outs

I had some great fun trying to work it out, but I don't have any idea of what is going on.

With the earphone plugged in you hear only a static noise, like a bad selected radio station.

I plugged the iPod on a dock station: same problem throughout the speakers of the dock.

I tried reset, recover, reinstall and nothing works.

At last, I've opened it, cleaned some contacts using lc-150, close it and the noise is still there.

It had dropped on the floor once.

It not even one year old.

Any help please?