TomTom one 1st addition?

I think Ive fried it, had the cig lighter power cable set too high (12v) when it should be 5v?, if I connect it to the mains charger, the green light comes on, but will not turn on, unplug it and there is nothing, left it charging overnight, still nothing. Tried re setting it, nothing. Is there a fuse or something inside that I can trip or replace, or do I just bin it and but a new one?