My ipod is frozen with nothing but the play symbol, the battery symbol all on a white background

Something has happened to my ipod whilst it was on my ipod dock.

Im not sure exactly what happened it but has appears to have frozen with a very badly (or simple) black pixilated image of a battery symbol, the play symbol and time of '12.15' on it and all of this on white background. This happen a few weeks ago.

i thought i would try and let my battery flatten and try and re-charge and even restoring it again via my computer but the battery has not flattened yet

Im not sure what this means an dont know what to do next. Please help. Thank you