IPOD nano (3rd gen) plays music-no screen tho

Hello,

I recently found my lost ipod. It had no charge and so I charged it at my pc. iTunes recognises it and lets me add music to it. When disconnected from the computer- it even PLAYS music perfectly now.
... BUT...
The screen backlight comes up as i turn it on (as though normal) but the entire screen is scrambled. Everything simply goes from black (off) to multicoloured horizontal lines (on).

Does anyone know what I could do to sort the screen out, please?

I have tried the holding down of home and play together for up to 2 minutes, even gently hitting the apple logo on the back as a last option for resetting (which is actually the way that I got the music to play)
So it plays, but the screen is screwed.
Please help, if you can.