I suspect the answer is 'it is fried' but...
I plugged 3 or 4.5 volts, backwards into a toy (remote control -> http://www.elc.co.uk/My-First-Gadget-Set/134518,default,pd.html ) and I'm pretty sure it is dead.
Is there any hope for such a thing? I'm frustrated, as I already had it in a track, and I'd done a time consuming job bending a SMD board... grr
J
What was supplying the power? If it was a power supply then its probably gone up in smoke, if it was batteries, maybe not.